Iamgold Reports Additional High Grade Intersections from the Delineation Drilling Program ON the Saramacca Project, Suriname

NEWS RELEASE

TSX: IMG NYSE: IAG

IAMGOLD REPORTS ADDITIONAL HIGH GRADE INTERSECTIONS FROM THE DELINEATION

DRILLING PROGRAM ON THE SARAMACCA PROJECT, SURINAME

Toronto, Ontario, May 15, 2017 – IAMGOLD Corporation (“IAMGOLD” or the “Company”) today

provided an update from its 2017 infill drilling program at the Saramacca project, located 25 kilometres

southwest of its Rosebel Gold Mine (“RGM”) in Suriname. The current phase of the 2017 infill delineation

drilling program is now complete with 113 diamond drill holes totaling approximately 19,600 metres. Assay

results have been received from 78 drill holes totaling 14,166 metres, including 49 drill holes totaling 8,158

metres reported herein (see previous news release dated March 29th, 2017). Assay results from the

remaining drill holes are expected in June and will be reported once they are validated and compiled.

The assay intersections including capped composites and estimated true widths are provided in Table 1

and include the following highlights:

(A drill hole plan map and select drill sections are attached to this news release.)

 SMDD17-138: 43.5 metres grading 12.26 g/t Au

 SMDD17-110: 76.6 metres grading 7.74 g/t Au

 SMDD17-130: 46.5 metres grading 3.07 g/t Au

 SMDD17-133: 45.4 metres grading 2.38 g/t Au

 SMDD17-097: 45.0 metres grading 2.70 g/t Au

 SMDD17-125: 31.0 metres grading 3.81 g/t Au

“The results to date support our belief that Saramacca has the potential to be a transformational asset for

the Company,” said President and CEO of IAMGOLD Steve Letwin. “This exemplifies our strategy of

seeking short-cycle capacity, which can add tremendous value for our shareholders at minimal incr emental

cost, since the deposit is only 25 kilometres away from our current infrastructure.”

Craig MacDougall, Senior Vice President, Exploration for IAMGOLD, stated: “ I want to congratulate the

exploration team for completing this important program in such a timely manner and without a reported

safety incident. The additional assay results continue to impress and highlight numerous intersections with

high grades of gold over wide intervals, both enhancing our confidence in and understanding of the

mineralized zones. As previously stated, all results will be incorporated into an initial resource estimation

expected for completion in Q3 2017.”

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2017 Exploration Program

Drilling to date has confirmed the presence of multiple mineralized structures within an approximately 2-

kilometre long and 600-metre wide corridor. Mineralization occurs in the near surface oxidized weathering

profile to depths ranging from 50 to 100 metres, as well as deeper in the primary sulphide zones and

remains open along strike and at depth. In the deposit area, three mineralization styles are recognized

from the drilling completed to date: breccia hosted mineralization characterized by jigsaw, crackle and

matrix supported breccias; shear hosted mineralization characterized by well-developed pyritic

disseminations and stringers; and irregular pyrite-quartz-carbonate veins which locally carry high gold

grades.

The 2017 50 x 50 metre infill drilling program has been completed and further drilling activities will await

the completion of the seasonal rains which have commenced. Results to date and those still pending will

be incorporated into a deposit model to support an initial National Instrument 43-101 resource estimate

expected for completion by the third quarter 2017. Additional exploration potential exists at depth and

along strike and will be tested in future drilling programs.

Preliminary engineering and permitting studies have commenced to support and develop future

exploitation scenarios.

About the Saramacca Project

The Saramacca project is strategically located approximately 25 kilometres southwest of the Rosebel Gold

Mine milling facility. Mineralization is hosted in the Paramaka Formation within the lower part of the

Marowijne Greenstone Belt, which is dominated by metamorphosed dacite, rhyolite, basalt and andesite

lithologies in the project area. These are traversed by the regional, northwest trending Saramacca shear

zone, an important deformation zone for the localization of gold mineralization.

The Saramacca property has been explored since the 1990’s principally by Golden Star Resources Ltd.

(“Golden Star”) and later as a joint venture between Golden Star and Newmont Mining Corporation. Much

of that work focused on the discovery and delineation of Anomaly M, which was the subject of successive

auger and diamond drilling programs with over 50 diamond drill holes and over 200 auger hol es completed

in the anomaly area. Evaluation of this work suggests an exploration target potential of between 8 and 40

million tonnes grading between 1.0 and 1.8 g/t Au for potentially 0.5 to 1.4 million contained ounces of

gold. The potential quantity and grade are conceptual in nature and insufficient exploration work has been

completed to date to define a mineral resource. The property will require significant future exploration to

advance to a resource stage and there can be no certainty that the exploration target will result in a

mineral resource being defined.

On August 30, 2016, the Company signed a letter of intent with the Government of Suriname to acquire

rights to the Saramacca property, with the intent of defining a National Instrument 43-101 mineral resource

within 24 months. The terms of the letter included an initial payment of $0.2 million, which enabled

immediate access to the property for Rosebel’s exploration team to conduct due d iligence, as well as

access to the data from previous exploration activity at the Saramacca property. On September 30, 2016,

having been satisfied with the results of the due diligence, the Company ratified the letter of intent to

acquire the Saramacca property and subsequently paid $10 million in cash and agreed to issue 3.125

million IAMGOLD common shares to the Government of Suriname in three approximately equal annual

instalments on each successive anniversary of the date the right of exploration was transferred to Rosebel

(December 14, 2016). In addition, the agreement provides for a potential upward adjustment to the

purchase price based on the contained gold ounces identified by Rosebel in National Instrument 43-101

measured and indicated resource categories, within a certain Whittle shell within the first 24 months, to a

maximum of $10 million.

The Saramacca project falls within the “UJV” area as defined in an Agreement with the Government of

Suriname announced on April 15, 2013. The Agreement establishes a joint venture growth vehicle under

which Rosebel would hold a 70% participating interest and the Government will acquire a 30%

participating interest on a fully-paid basis.

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Qualified Persons and Technical Information

The drilling results contained in this news release have been prepared in accordance with National

Instrument 43-101 Standards of Disclosure for Mineral Projects ("NI 43-101").

The "Qualified Person" responsible for the supervision of the preparation , verification and review of the

technical information in this release is Ian Stockton, MAusIMM, FAIG, RP. Geo., Exploration Manager for

IAMGOLD in Suriname. He is considered a "Qualified Person" for the purposes of National Instrument 43 -

101 with respect to the technical information being reported on. The technical information has been

included herein with the consent and prior review of the above noted Qualified Person.

The information in this news release was reviewed and approved by Craig MacDougall, P.Geo., Senior

Vice President, Exploration for IAMGOLD. Mr. MacDougall is a Qualified Person as defined by National

Instrument 43-101.

The sampling of, and assay data from, drill core is monitored through the implementation of a quality

assurance - quality control (QA-QC) program designed to follow industry best practice. Drill core (HQ and

NQ size) samples are selected by the IAMGOLD geologists and sawn in half wi th a diamond saw at the

Rosebel mine site. Half of the core is retained at the site for reference purposes. Sample intervals may

vary from half a metre to one and a half metres in length depending on the geological observations.

Samples are transported in sealed bags to FILAB in Paramaribo, Suriname, a representative lab of ALS.

FILAB is an ISO 9001 (2008) and ISO/IEC 170250 accredited laboratory. Samples are weighed and

coarse crushed to <2.5 mm, and 350-450 grams is pulverized to 85% passing <100 μm. Samples are

analyzed for gold using standard fire assay technique with a 50 gram charge and an Atomic Absorption

(AA) finish. IAMGOLD inserts blanks and certified reference standard in the sample sequence for quality

control. Samples representative of the various lithologies are collected from each drill hole and measured

for bulk density at the site RGM laboratory.

Forward Looking Statement

This news release contains forward-looking statements. All statements, other than of historical fact, that

address activities, events or developments that the Company believes, expects or anticipates will or may

occur in the future (including, without limitation, statements regarding expected, estimated or planned gold

production, cash costs, margin expansion, capital expenditures and exploration expenditures and

statements regarding the estimation of mineral resources, exploration results, potential mineralization,

potential mineral resources and mineral reserves) are forward-looking statements. Forward-looking

statements are generally identifiable by use of the words “will”, “should”, “continue”, “expect”, “estimate”,

“believe”, “plan” or “project” or the negative of these words or other variations on these words or

comparable terminology. Forward-looking statements are subject to a number of risks and uncertainties,

many of which are beyond the Company’s ability to control or predict, that may cause the actual results of

the Company to differ materially from those discussed in the forward-looking statements. Factors that

could cause actual results or events to differ materially from current expectations include, among other

things, without limitation, failure to meet expected, estimated or planned gold production, cash costs,

margin expansion, capital expenditures and exploration expenditures and failure to establish estimated

mineral resources, the possibility that future exploration results will not be consistent with the Company's

expectations, changes in world gold markets and other risks disclosed in IAMGOLD’s most recent Form

40-F/Annual Information Form on file with the United States Securities and Exchange Commission and

Canadian provincial securities regulatory authorities. Any forward-looking statement speaks only as of the

date on which it is made and, except as may be required by applicable securities laws, the Company

disclaims any intent or obligation to update any forward-looking statement.

About IAMGOLD

IAMGOLD (www.iamgold.com) is a mid-tier mining company with four operating gold mines on three

continents. A solid base of strategic assets in North and South America and West Africa is complemented

by development and exploration projects and continued assessment of accretive acq uisition opportunities.

IAMGOLD is in a strong financial position with extensive management and operational expertise.

page 4 of 8

For further information please contact:

Ken Chernin, VP Investor Relations, IAMGOLD Corporation

Tel: (416) 360-4743 Mobile: (416) 388-6883

Laura Young, Director, Investor Relations, IAMGOLD Corporation

Tel: (416) 933-4952 Mobile: (416) 670-3815

Shae Frosst, Investor Relations Associate, IAMGOLD Corporation

Tel: (416) 933-4738 Mobile: (647) 967-9942

Toll-free: 1-888-464-9999 [email protected]

Please note:

This entire news release may be accessed via fax, e -mail, IAMGOLD's website at www.i amgold.com and through CNW Group’s

website at www.newswire.ca. All material information on IAMGOLD can be found at www.sedar.com or at www.sec.gov.

Si vous désirez obtenir la version française de ce communiqué, veuillez consulter le

http://www.iamgold.com/French/accueil/default.aspx.

page 5 of 8

Table 1: Diamond Drill Hole Assay Results

HOLE-ID

Local Grid End of hole

(m)

Azimuth

(°)

Dip

(°) From (m) To (m) Interval (m) True Width (m)3 Au (g/t)

Au (g/t)

(capped at 30

g/t Au)2 Easting Northing Elevation

SMDD17-096 32215 64071 802 183.0 250 -50 126.5 144.5 18.0 10.0 1.79 1.79

SMDD17-097 32021 64231 770 94.0 250 -50 12.0 57.0 45.0 24.0 2.70 2.70

SMDD17-098 Disclosed in previous press release (March 29th)

SMDD17-099 32224 63998 826 102.0 215 -50 No significant results

SMDD17-100 31928 64527 717 136.5 215 -50 No significant results

SMDD17-101 32844 63315 901 278.0 215 -50 0.0 7.0 7.0 4.0 2.20 2.20

196.0 216.5 20.5 11.0 4.18 4.18

243.0 262.3 19.3 10.0 2.60 2.60

SMDD17-102 32249 64033 807 156.0 215 -47 121.0 130.0 9.0 5.0 0.55 0.55

SMDD17-103 32041 64259 754 23.5 215 -50 0.0 7.0 7.0 4.0 0.49 0.49

SMDD17-104 32120 64371 725 314.0 215 -47 25.5 31.5 6.0 4.0 0.80 0.80

96.0 123.5 27.5 17.0 1.20 1.20

159.0 165.5 6.5 4.0 0.48 0.48

252.5 261.5 9.0 6.0 1.07 1.07

SMDD17-105 32342 63991 817 87.0 215 -50 39.0 47.5 8.5 4.0 4.75 4.75

SMDD17-106 32341 63815 876 90.0 215 -50 No significant results

SMDD17-107 32435 63777 881 150.0 215 -50 0.0 12.0 12.0 7.0 4.55 4.55

96.5 117.5 21.0 11.0 2.57 2.57

SMDD17-108 31799 64607 691 163.5 0 0 13.5 19.5 6.0 3.0 0.55 0.55

SMDD17-109 32819 63193 914 138.5 215 -50 13.0 22.0 9.0 5.0 0.61 0.61

74.0 98.0 24.0 13.0 2.02 2.02

SMDD17-110 32360 63844 865 124.5 215 -50 0.9 77.5 76.6 41.0 7.74 7.74

SMDD17-111 31772 64569 694 109.5 215 -47 0.0 6.0 6.0 3.0 0.62 0.62

SMDD17-112 32868 63263 901 251.0 0 0 2.0 19.0 17.0 8.0 1.65 1.65

28.0 34.0 6.0 3.0 0.68 0.68

74.5 89.5 15.0 8.0 1.04 1.04

203.5 217.0 13.5 7.0 3.82 3.82

223.0 244.0 21.0 11.0 1.63 1.63

SMDD17-113 32382 63788 877 142.5 215 -50 No significant results

SMDD17-114 31777 64480 697 110.0 35 -50 No significant results

SMDD17-115 32306 63685 883 190.5 35 -50 156.0 166.5 10.5 6.0 3.08 3.08

SMDD17-116 32137 64214 761 231.0 215 -50 No significant results

SMDD17-117 32822 63025 868 154.0 35 -50 No significant results

SMDD17-118 32151 64239 748 257.0 215 -50 101.5 106.5 5.0 3.0 2.20 2.20

SMDD17-119 32397 63635 894 159.0 35 -50 111.0 117.1 6.1 3.0 0.46 0.46

123.0 129.0 6.0 3.0 4.30 4.30

136.5 144.1 7.6 4.0 0.42 0.42

SMDD17-120 32912 63155 899 155.5 35 -50 85.0 91.5 6.5 4.0 2.21 2.21

SMDD17-121 32524 63735 865 253.5 215 -50 No significant results

SMDD17-122 32043 64255 754 164.0 215 -50 111.5 126.5 15.0 8.0 5.45 5.45

SMDD17-123 32776 63221 915 127.0 215 -50 No significant results

SMDD17-124 32647 63555 895 196.0 215 -50 0.0 9.5 9.5 5.0 1.92 1.92

170.5 185.5 15.0 8.0 0.97 0.97

SMDD17-125 32062 64288 739 239.0 215 -48 148.0 179.0 31.0 18.0 3.81 3.81

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HOLE-ID Local Grid End of hole

(m)

Azimuth

(°)

Dip

(°) From (m) To (m) Interval (m) True Width (m) Au (g/t)

Au (g/t)

(capped at 30

g/t Au)

SMDD17-126 32503 63699 866 181.5 215 -50 0.0 8.4 8.4 5.0 2.99 2.99

63.2 70.5 7.3 4.0 6.23 6.23

138.0 146.3 8.3 4.0 2.79 2.79

SMDD17-127 31920 64476 729 145.5 215 -50 1.5 9.4 7.9 4.0 0.73 0.73

78.0 84.8 6.8 4.0 1.32 1.32

SMDD17-128 32628 63528 899 178.5 215 -50 0.0 8.9 8.9 5.0 5.75 5.75

98.0 106.5 8.5 5.0 0.57 0.57

125.0 136.5 11.5 6.0 4.05 4.05

SMDD17-129 32307 63684 883 175.5 35 -50 154.3 163.5 9.2 5.0 8.15 8.15

SMDD17-130 32083 64317 724 261.0 215 -50 0.0 7.5 7.5 4.0 0.49 0.49

93.0 100.5 7.5 4.0 1.27 1.27

123.0 138.0 15.0 9.0 1.24 1.24

163.5 171.0 7.5 5.0 0.48 0.48

180.0 226.5 46.5 30.0 3.07 3.07

SMDD17-131 32603 63494 905 96.0 215 -50 No significant results

SMDD17-132 32482 63669 866 87.0 215 -50 39.0 52.5 13.5 8.0 3.61 3.61

SMDD17-133 31821 64380 725 178.5 35 -50 119.6 165.0 45.4 30.0 2.38 2.38

SMDD17-134 32603 63322 916 180.0 35 -50 109.0 133.5 24.5 16.0 3.13 3.13

SMDD17-135 32614 63683 877 348.0 215 -50 232.5 238.5 6.0 3.0 2.13 2.13

SMDD17-136 31901 64406 744 76.5 215 -53 No significant results

SMDD17-137 32792 63067 881 168.0 35 -50 106.5 112.5 6.0 4.0 0.89 0.89

126.0 133.5 7.5 4.0 0.93 0.93

SMDD17-138 31892 64221 771 243.0 215 -50 151.5 195.0 43.5 22.0 12.26 5.52

SMDD17-139 32767 63034 876 207.0 35 -50 116.0 133.5 17.5 11.0 0.93 0.93

150.0 157.6 7.6 5.0 0.90 0.90

178.5 187.5 9.0 6.0 4.84 4.84

SMDD17-140 32129 64123 804 120.5 215 -50 No significant results

SMDD17-141 32843 63054 873 99.0 35 -50 No significant results

SMDD17-142 32694 63363 899 168.0 215 -50 1.2 10.5 9.4 4.9 4.71 4.71

SMDD17-144 32577 63545 902 144.0 215 -50 No significant results

SMDD17-145 31915 64427 737 100.5 215 -50 No significant results

SMDD17-146 32695 63451 890 220.5 215 -50 0.0 5.9 5.9 3.0 0.36 0.36

134.4 148.3 13.9 7.0 4.81 4.81

Notes:

1. Drill hole intercepts are calculated using a 0.50 g/t Au assay cut-off and 5m minimum length

2. During compositing, assays greater than 30 g/t Au are capped at 30 g/t Au

3. True widths are estimated from intersected geometries

page 7 of 8

Figure 1: Saramacca drill hole plan map and highlighted 2017 assay results.

page 8 of 8

Figure 2: Saramacca cross section 1750NW

Figure 3: Saramacca cross section 600NW