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Iamgold Reports Further High Grade Results from the Monster Lake Project, Quebec

Drill Results

NEWS RELEASE

TSX: IMG NYSE: IAG

IAMGOLD REPORTS FURTHER HIGH GRADE RESULTS FROM THE

MONSTER LAKE PROJECT, QUEBEC

Toronto, Ontario, July 6, 2017 – IAMGOLD Corporation (“IAMGOLD” or the “Company”) today provided

the remaining assay results from the winter 2017 drilling program completed at its Monster Lake joint

venture project located 50 kilometres southwest of Chibougamau, Quebec, Canada. The company is

reporting the assay results from the final fourteen drill holes, totaling just over 5,400 metres, from a total of

25 diamond drill holes, totaling 10,657 metres, completed this past winter.

The assay results are provided in Table 1 below and include the following highlights:

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

Monster Lake Shear Zone, Megane Zone and Annie Shear Zone:

 Drill hole ML17-197: 3.5 metres grading 67.42 g/t gold

o Includes: 1.2 metres grading 203.31 g/t gold

 Drill hole ML17-198B: 5.0 metres grading 80.28 g/t gold

o Includes: 1.8 metres grading 208.41 g/t gold

Lower Shear Zone:

 Drill hole ML17-199: 1.6 metres grading 39.48 g/t gold

o Includes: 0.9 metres grading 66.50 g/t gold

The 2017 winter drilling program was designed to target high potential areas along the 3 -kilometre trend of

the Monster Lake Structural Corridor (“MLSC”) and associated s hear zones to improve confidence and

expand known zones of mineralization, as well as better define more recent discoveries such as the new

zone located 200 to 400 metres to the north of the Megane Zone, as well as mineralization discovered within

a parallel structure, the Lower Shear Zone, that has returned encouraging initial results. Interpretation of the

structural setting suggests favourable potential for the occurrence of additional mineralized shoots along this

major structural corridor.

The results from this drilling program ha ve demonstrated continuity of very high grade s of mineralization

associated with the Megane Zone where tested with infill diamond drill holes. They have also extended

mineralization in the northern part of th e mineralized shoot with positive results obtained from holes ML17-

197 and ML17-201B. As well, new areas of mineralization to the nor th of the Me gane Zone, which appear

to be associated with multiple mineralized shear zones , will require further drill testing to evaluate the

potential of this area . The most recent assay results received from drill holes intersecting the Lower Zone

hosted in a parallel shear zone northwest of the Megane Zone are also considered encouraging and include

hole ML-17-191 which intersected 85.27 g/t Au over 1.8 metres (see press release dated May 11, 2017) and

hole ML-17-199 which intersected 39.48 g/t Au over 1. 6 metres.

Craig MacDougall, Senior Vice President, Exploration for IAMGOLD, stated : “With all assay results now in

hand from our winter campaign, we are working to revise the deposit model to better understand the resource

potential of the Megane Zone. Importantly, the drilling program has continued to identify new areas of gold

mineralization along the main shear and associated with parallel structures, again reinforcing our view of the

favourable potential for the discovery of additional mineralized zones.”

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Next Steps

In the coming weeks, a 1,600 metre diamond drilling program is planned to test the gold bearing structures

from areas accessible in the summer season. The program will specifically target the Lower zone as well

as complete additional infill holes at the Megane zone. The results will be incorporated into the deposit

model and may lead to the completion of an initial mineral resource estimate by yearend. Further drilling

will be required to evaluate the potential of the new mineralized areas and are scheduled for next winter.

About the Monster Lake Project

The Monster Lake project is underlain by Archean volcanic rocks of the Obatogamau Formation and is

traversed by an important deformation corridor and associated gold-bearing mineralized structures.

Historical drilling and exploration by TomaGold Corporation (“TomaGold’) have identified a four-kilometre

long structural corridor, along which most of the known gold occurrences discovered to date on the

property are associated, including the Megane Zone.

IAMGOLD holds a 50% interest in the Monster Lake project. Pursuant to an earn-in option agreement with

TomaGold amended on October 30, 2015, IAMGOLD holds an option to earn a further 25% undivided

interest, for a total 75% undivided interest in the project, should it spend a further C$10.0 million on the

project within a seven-year period, beginning January 1, 2015. Should a development decision be made

by the joint venture, or should the joint venture declare commercial production, TomaGold would be

entitled to a further C$1.0 million payment. IAMGOLD has completed its first year commitment under the

terms of the amended option earn in agreement.

Technical Information and Quality Control Notes

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 and review of this information is

Marie-France Bugnon, P. Geo., General Manager Exploration. Marie-France 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 Qualified person has verified the data disclosed, and data unde rlying

the information or opinions contained herein.

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 (NQ size)

samples are selected by the IAMGOLD geologists and sawn in half with a diamond saw at the project 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 ALS Minerals Laboratory located in Val-d’Or,

Québec. Samples are coarse crushed to a -10 mesh and then a 1000 gram split is pulverized to 95%

passing -150 mesh. ALS Minerals processes analytical pulps directly at their facilities located in Val-d’Or

which is ISO / IEC 17025 certified by the Standards Council of Canada. Samples are analyzed using a

standard fire assay with a 50 gram charge with an Atomic Absorption (AA) fin ish. For samples that return

assay values over 5.0 grams per tonne (g/t), another pulp is taken and fire assayed with a gravimetric

finish. Core samples showing visible gold or samples which have returned values greater than 10.0 g/t are

re-analyzed by pulp metallic analysis. IAMGOLD inserts blanks and certified reference standard in the

sample sequence for quality control.

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”, “anticipate”,

“estimate”, “believe”, “intend”, “to earn”, “to have’, “plan” or “project” or the negative of these words or other

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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 s trategic assets in North and South America and West Africa is complemented

by development and exploration projects and continued assessment of accretive acquisition opportunities.

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

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.iamgold.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/Home/default.aspx.

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Table 1

Notes:

1. Drill hole intercepts are calculated using a 0.50 g/t Au assay cut-off.

2. True widths of intersections are approximately 60-90% of the core interval.

3. Assays are reported uncut but high grade sub-intervals are highlighted.

Hole No. AZ DIP EOH from To Interval True W idth (2) Au (1) NOTE

Easting Northing Elevation (°) (°) (m) (m) (m) (m) (m) (g/t)  

ML-1 4-1 1 6-EXT 54881 1 6.462 520000.531 2 369.21 1 4 1 39 -45 423 (extended

by 1 1 9m) 399.90 405.70 5.80 5.02 NSR Lower Shear Zone

ML-1 7-1 85 5488702.083 5201 43.7609 371 .31 54 290 -60 354 1 65.00 1 65.90 0.90 0.64 6.48 Main Shear Zone

1 72.50 1 74.35 1 .85 1 .31 2.1 4

272.60 273.00 0.40 0.28 6.60 Lower Shear Zone

ML-1 7-1 95B 5488372.421 5201 65.21 67 370.9754 285 -59 393 328.80 331 .60 2.80 1 .80 2.48 Main Shear Zone

ML-1 7-1 97 5488373.881 5201 65.3391 370.9558 31 0 -55 390 335.30 336.30 1 .00 0.77 1 0.05 Main Shear Zone

338.70 339.50 0.80 0.61 1 .90

342.00 344.30 2.30 1 .76 2.28

347.30 351.90 4.60 3.52 67.42

Including (3) 349.80 351.30 1.50 1.15 203.31

ML-1 7-1 98B 5488322.81 1 52031 4.0703 373.1 009 290 -50 51 9 96.00 97.00 1 .00 0.77 1 2.35

467.00 473.50 6.50 4.98 80.28 Main Shear Zone

Including (3) 470.30 472.70 2.40 1.84 208.41

478.80 479.85 1 .05 0.80 1 .34

ML-1 7-1 99 54881 1 6.656 5201 42.9305 370.1 1 1 3 301 -57 585 402.90 406.50 3.60 3.26 NSR Main Shear Zone

539.40 541.20 1.80 1.56 39.48 Lower Shear Zone

Including (3) 539.40 540.45 1.05 0.91 66.50

ML-1 7-200 5488670.966 520292.3765 371 .6393 293 -53 498 322.80 328.00 5.20 3.98 NSR Main Shear Zone

422.30 423.60 1 .30 1 .1 3 1 .47 Lower Shear Zone

ML-1 7-201 B 5488565.1 83 5201 26.1 31 6 370.7377 280 -75 342 271 .00 272.60 1 .60 1 .23 1 .01 Main Shear Zone

278.40 282.40 4.00 3.06 3.66

286.60 288.00 1 .40 1 .07 1 .24

ML-1 7-202 5489267.93 520623.81 64 375.9692 31 5 -50 392 245.40 246.70 1 .30 1 .22 1 .08 Annie Shear Zone

280.20 281 .40 1 .20 1 .1 3 3.91

ML-1 7-203 5488565.822 5201 25.5885 370.7421 290 -47 327 1 94.20 1 95.50 1 .30 1 .1 3 1 .27

209.00 209.90 0.90 0.78 3.73 Main Shear Zone

303.80 308.1 0 4.30 3.72 NSR Lower Shear Zone

ML-1 7-204 5489826.572 520939.6488 373.7997 31 5 -55 31 5 203.40 208.40 5.00 3.83 2.74 Annie Shear Zone

ML-1 7-205 5489729.821 520973.2074 375.2069 31 5 -55 351 No significant results Annie Shear Zone

ML-1 7-206 5488998.666 520344.4845 372.6063 335 -60 41 7 347.70 348.70 1 .00 0.64 1 .50 ML Shear Zone

357.50 358.90 1 .40 0.90 1 .27 Main Shear Zone

ML-1 7-207 5488998.32 520344.1 43 372.5386 325 -65 405 360.80 361 .80 1 .00 0.77 1 .42 Main Shear Zone

UTM NAD83 Zone1 8

M onster Lake P roject Drilling Final Results - 2017 W inter Drilling P rogram

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