An antimicrobial activity of Omphalotus olivascens wild mushroom was evaluated. The mycelia culture filtrate extracts showed varying degree of inhibition on the test organisms (Bacillus cereus, Escherichia coli, Salmonella paratyphi A, Klebsiella pnemoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Candida albicans).  The antimicrobial activity of mushroom sample varied according to the solvents. The ethyl acetate extract was the most active when compared with other extracts, to inhibit the growth of Acinetobacter baumannii (32mm), Klebsiella pnuemoniae (31mm), Bacillus cereus (31mm), and E.coli (28mm), Pseudomonas aeruginosa (28mm) Salmonella paratyphi A (27mm) and Canidida albicans (24mm). The bioactive contents of the mushroom are promising natural antimicrobial agents that can be harnessed as antimicrobial toxicants.