MONTREAL, QUEBEC--(Marketwire - Sept. 23, 2009) - Osisko Mining Corporation ("Osisko") (TSX:OSK)(FRANKFURT:EWX) is pleased to announce partial drilling results from the Q2-Q3 2009 drill program within the model pit on the South Barnat deposit. Following the release of the South Barnat Measured and Indicated resource estimate (June 2, 2009 press release), the Company proceeded with a phase three definition drill program on deeper portions of known mineralized zones within and below the Whittle-optimized pit shell. This was accompanied by a condemnation drill program designed to test presumed barren, outer portions of the model pit for additional mineralization. Unanticipated gold mineralization was encountered in a number of locations, pointing to the potential for expansion of the in-pit resource at Barnat. All results reported below were not included in the June 2, 2009 resource estimate.

Significant new drill intersections include 2.16 g/t Au over 129.5 metres (BA08-3611), 1.23 g/t Au over 88.0 metres (BA08-3554E) and 1.11 g/t Au over 176.2 metres (BA08-3663). Highlights from new infill holes on known mineralized zones are tabled below:

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  Hole No.       Section     From (m)     To (m)     Length (m)     Au g/t


BA09-3554E        BA550E         8.8       28.0           19.2        0.79
       and                     161.5      249.5           88.0        1.23
       and                     332.0      383.5           51.5        1.64
 including                     368.0      369.5            1.5       13.30


 BA09-3571        BA775E       290.0      320.0           30.0        1.20 
       and                     378.5      405.6           27.1        1.18


 BA09-3590        BA500E       254.5      288.0           33.5        0.84


 BA09-3603        BA550E       307.5      354.0           46.5        1.87


 BA09-3607        BA050E        23.0      112.3           89.3        0.90


 BA09-3611        BA600E       272.5      402.0          129.5        2.16
 including                     334.0      340.0            6.0        7.92


 BA09-3625        BA425E         7.1      122.5          115.4        0.88
       and                     149.5      159.9           10.4        16.5


 BA09-3626        BA425E        57.2       99.0           41.8        1.47
       and                     136.9      145.1            8.2        3.52
       and                     167.5      198.3           30.8        2.42
 including                     195.8      196.8            1.0       12.15


 BA09-3636        BA650E       269.0      321.5           52.5        1.19
       and                     390.5      420.5           30.0        1.16


 BA09-3663        BA525E        21.0       37.0           16.0        1.30
       and                     103.0      279.2          176.2        1.11
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Significant drill intersections from new mineralized zones located on the outer margins of the model pit include 2.72 g/t Au over 25.4 metres (BA08-3577), 0.60 g/t Au over 107.5 metres (BA08-3632) and 0.83 g/t Au over 91.5 metres (BA08-3638). Highlights from the intersections in new mineralized zones are tabled below:

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  Hole No.       Section     From (m)     To (m)     Length (m)     Au g/t 


 BA09-3561       CM5800E       272.0      284.4           12.4        4.57


 BA09-3565        BA325E        51.0       93.5           42.5        0.77


 BA09-3577        BA550E        70.9       96.3           25.4        2.72
 including                      70.9       72.5            1.6       19.05


 BA09-3600        BA625E        41.1       68.4           27.3        1.38


 BA09-3630        BA625E        55.5      105.0           49.5        0.73


 BA09-3632        BA150E       112.5      220.0          107.5        0.60
       and                     246.0      259.5           13.5        0.71


 BA09-3633        BA775E       244.0      291.5           47.5        1.49
 including                     245.5      247.0            1.5       13.50


 BA09-3637        BA650E        16.0      108.0           92.0        0.75


 BA09-3638        BA650E        22.0      113.5           91.5        0.83


 BA09-3639        BA575E        30.5       52.0           21.5        1.16


 BA09-3641        BA600E        36.0       55.5           19.5        0.99
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The mineralized intersections in drill holes BA09-3561 and BA09-3633 and the second intersection in drill hole BA09-3632 are below current pit model limits.

Results from this drill program on South Barnat are being integrated into a new data base along with new drill results from the Southeastern Extension of the Canadian Malartic deposit. The new data base will be used to calculate an updated global resource, from which a new reserve estimate in a merged engineered pit will be calculated for the combined Canadian Malartic and South Barnat deposits. This new reserve estimate is scheduled to be released by year end.

All NQ or HQ core assays reported above were obtained by standard 50 g fire assaying-AA finish or gravimetric finish at ALS Chemex laboratories in Val d'Or, Quebec. Reported weighted averages were calculated using a minimum of 0.50 g/t Au over successive maximum intervals of 20 metres with no upper cut-off of individual assays. Intersected drifts or lost core within mineralized intersections were incorporated as blank intervals.

Osisko Mining Corporation is currently developing the Canadian Malartic gold deposit and evaluating adjacent areas for a large-scale open pit, bulk-tonnage mining operation. The Canadian Malartic deposit currently represents one the biggest gold reserves in Canada for a single deposit, and is still growing through ongoing drilling on new mineralized zones. Current reserves for the Canadian Malartic property are 6.28 million ounces, plus (including the Barnat deposit) a measured and indicated resource of 3.65 million ounces and an inferred resource of 0.84 million ounces. Mr. Robert Wares, P. Geo. and Executive Vice-President of Osisko, is the Qualified Person who has reviewed this news release and is responsible for the technical information reported herein, including verification of the data disclosed including the sampling, analytical and test data underlying the technical information.