Klondex Drilling at Fire Creek Intercepts 13.5 opt (461.6 g/T) Over 11.5 Feet (3.5 Metres); Begins Development for Long Hole Stoping on Hui Wu Vein

VANCOUVER, BC--(Marketwired - May 21, 2015) -

Highlights of Hui Wu Vein:

• 13.5 opt (461.6 g/T) AuEq over 11.5 ft (3.5 metres) - FCU-0214
• 5.1 opt (174.3 g/T) AuEq over 3.2 ft (1.0 metres) - FCU-0328
• 64.0 opt (2,194.7 g/T) AuEq over 1.1 ft (0.3 metres) - FCU-0357
• 1.5 opt (52.7 g/T) AuEq over 12.3 ft (3.7 metres) - FCU-0213
• 2.1 opt (72.0 g/T) AuEq over 4.4 ft (1.3 metres)- FCU-0360

Klondex Mines Ltd. (TSX: KDX)(OTCQX: KLNDF) ("Klondex" or the "Company") provides an update on recent drilling and development on the Hui Wu Vein at its Fire Creek project in northern Nevada.

Drill assays (SEE TABLE 1) from 19 core holes drilled in 2015 were recently received indicating significant gold intercepts in the north end of the Hui Wu Vein. These holes, targeting the Hui Wu Vein and Joyce Vein, were predominately drilled east from the north end of the Karen Vein. Based on the assay results, it was determined that the Hui Wu could be accessed and developed along the vein.

Development began in April near the north end of the Hui Wu Vein and was excavated north 139 feet (42.4 metres) along the vein (SEE FIGURES). The average fully-diluted grade mined was 1.0 AuEq opt (34.5 g/T) over an average sill width of 7 feet (2.1 metres) (SEE TABLE 2) compared to the modeled mineral resource grade of 0.47 opt AuEq (16.1 g/T) in the Hui Wu Vein (see Fire Creek Pre-feasibility Study, with an effective date of December 31, 2014). Development of a top cut for long-hole stoping of the Hui Wu Vein began in May.

Brian Morris, Klondex VP Exploration, comments: "These results continue to demonstrate the high grade nature of the Fire Creek deposit and its exploration opportunity. Assay results from development on the Hui Wu Vein compare favorably to the predicted M&I mineral resource grade of 0.47 opt AuEq. Additionally, the recent drilling was not included in the mineral reserve estimates but is expected to be included in the updated mine plans for Q3. We are continuing the exploration drift to the north, as per schedule, with drill results expected to be released in the second half of 2015."