Klondex Provides Underground Drill Update at Fire Creek; Continues to Extend High Grade Vein System Along Strike

VANCOUVER, BC--(Marketwired - September 14, 2017) - Klondex Mines Ltd. (TSX: KDX) (NYSE American: KLDX) ("Klondex" or the "Company") is pleased to provide an update on the 2017 underground drill results at its Fire Creek Mine ("Fire Creek") located in northern Nevada, USA. The following drill results are not included in the current Mineral Resource estimate.

Fire Creek Mine Underground Drilling Highlights: (see TABLE 1 for complete results)

North

• FCU-0749: 0.91 opt Au over 6.3 ft, or 31.21 g/t over 1.9 m - Honeyrunner/Vein 59
• FCU-0738: 1.12 opt Au over 1.3 ft, or 38.50 g/t over 0.4 m - Karen
• FCU-0769: 0.77 opt Au over 17.3 ft, or 26.25 g/t over 5.3 m - Honeyrunner/Vein 55
• FCU-0711: 0.32 opt Au over 32.5 ft, or 10.95 g/t over 9.9 m - Honeyrunner

Up-Dip

• FCU-0850: 1.61 opt Au over 5.0 ft, or 55.13 g/t over 1.5 m - Joyce
• FCU-0752: 2.68 opt Au over 1.5 ft, or 91.81 g/t over 0.5 m - Vein 31
• FCU-0804: 1.32 opt Au over 1.3 ft, or 45.33 g/t over 0.4 m - Honeyrunner
• FCU-0780: 0.45 opt Au over 31.2 ft, or 15.48 g/t over 9.5 m - Vein 21

South

• FCU-0822: 3.56 opt Au over 1.5 ft, or 122.01 g/t over 0.5 m - Vein 39
• FCU-0821: 1.70 opt Au over 1.3 ft, or 58.22 g/t over 0.4 m - Vein 39
• FCU-0733: 1.60 opt Au over 1.0 ft, or 55.01 g/t over 0.3 m - Vein 45
• FCU-0823A: 0.84 opt Au over 11.8 ft, or 28.69 g/t over 3.6 m - Vein 39/Joyce
  Including 1.66 opt Au over 2.2 ft, or 56.81 g/t over 0.7 m and
  Including 3.33 opt Au over 1.3 ft, or 114.01 g/t over 0.4 m

Key Points: (FIGURE 1)
Assay results have been received for 165 underground drill holes totaling 127,720 ft (38,929.1 m). This drilling focused primarily on increasing the confidence level in the current Mineral Resource estimate as well as extending mineralization to the north, south and up-dip. Assay results continue to support high grade mineralization continuity along strike and vertically.

North (FIGURE 2)
Drilling continued to test the northern and down dip extensions of veins 31, Honeyrunner and Karen from the northern most portion of the mine workings. Results show high grades and wide drilled widths offering an opportunity for future bulk tonnage mining. Continuous mineralization on multiple veins has been extended to the north along strike by approximately 750 ft (228.6 m) and 500 ft (152.4 m) down dip.

Up-Dip (FIGURES 3, 4, 5)
The up-dip drilling along Joyce, Joyce Splay, Karen, Honeyrunner and Vein 21 has returned significant assay results along a cumulative strike of approximately 1,000 ft (304.8 m). Mineralization has been extended up-dip above the existing mine workings by 50 to 200 ft (15.2 to 61.0 m). Assays suggest mineralization continues with similar grades and widths to what has traditionally been mined along these veins.

South (FIGURE 5)
The drilling to the southwest has shown a cluster of significant assays on previously known and unknown veins. These veins are approximately 200 ft (61.0 m) from current mine workings and will be an area of focus in the 2018 drill program.

Assays were performed by ALS Global of Reno, Nevada and American Assay Laboratories of Sparks, Nevada, as directed under the supervision of Klondex staff. These organizations are ISO 17025 accredited independent laboratories.

A description of the data verification methods, quality assurance program and quality control measures applied can be found in the technical report titled "Technical Report for the Fire Creek Project, Lander County, Nevada" dated March 28, 2016 and with an effective date of June 30, 2015 which is available under the Company's issuer profile on SEDAR at www.sedar.com.

About Klondex Mines Ltd. (www.klondexmines.com)
Klondex is a well-capitalized, junior-tier gold and silver mining company focused on exploration, development, and production in a safe, environmentally responsible, and cost-effective manner. The Company has 100% interests in three producing mineral properties: the Fire Creek Mine and the Midas Mine and ore milling facility, both of which are located in the state of Nevada, USA, and the True North Gold Mine and mill in Manitoba, Canada. The Company also has 100% interests in two recently acquired projects, the Hollister mine and the Aurora mine and ore milling facility, also located in Nevada, USA.

Qualified Person
Scientific and technical information in this press release has been reviewed and approved by Brian Morris (AIPG CPG-11786), a "qualified person" within the meaning of NI 43-101.

Cautionary Note Regarding Forward-looking Information
This news release contains certain information that may constitute forward-looking information or forward-looking statements under applicable Canadian and United States securities legislation (collectively, "forward-looking information"), including but not limited to the exploration potential at the Fire Creek Mine and future exploration and production plans of Klondex. This forward-looking information entails various risks and uncertainties that are based on current expectations, and actual results may differ materially from those contained in such information. These uncertainties and risks include, but are not limited to, the strength of the global economy; the price of gold; operational, funding and liquidity risks; the degree to which mineral resource estimates are reflective of actual mineral resources; the degree to which mineral reserve estimates are reflective of actual mineral reserves; the degree to which factors which would make a mineral deposit commercially viable are present; the risks and hazards associated with underground operations; and the ability of Klondex to fund its substantial capital requirements and operations. Risks and uncertainties about the Company's business are more fully discussed in the Company's disclosure materials filed with the securities regulatory authorities in Canada and United States available at www.sedar.com and www.sec.gov, respectively. Readers are urged to read these materials. Klondex assumes no obligation to update any forward-looking information or to update the reasons why actual results could differ from such information unless required by law.

Image Available: http://www.marketwire.com/library/MwGo/2017/9/13/11G145464/Images/Figure1-b63bc293dab4b3caa07c80109468e493.jpg
Image Available: http://www.marketwire.com/library/MwGo/2017/9/13/11G145464/Images/Figure2-54fb01a7ac1b9ea185ec997c170b1adb.jpg
Image Available: http://www.marketwire.com/library/MwGo/2017/9/13/11G145464/Images/Figure3-5b527677d68abdc0b0a4d86805a12cf6.jpg
Image Available: http://www.marketwire.com/library/MwGo/2017/9/13/11G145464/Images/Figure4-0f8bacd0a685928fb81e7a0d700f50dc.jpg
Image Available: http://www.marketwire.com/library/MwGo/2017/9/13/11G145464/Images/Figure5-a6626e66ec37b19dbc16ae7a8d753c9b.jpg

Attachment Available: http://www.marketwire.com/library/MwGo/2017/9/13/11G145464/Copy_of_Fire_Creek_UG_PR_FINAL_2_(2)-3283053e4b7cb3cc98e6d7e99dceb6af.pdf