Protein-bound polysaccharopeptide (PSP) was extracted from submerged fermentation of Coriolus versicolor subculture and was investigated for in vitro antimicrobial activity. 3 Gram-positive and Gram-negative bacterial species and 1 yeast were analyzed for their susceptibility to PSP based on the Agar Hole Diffusion test. According to the results, 1/100 and 1/250 dilutions of PSP were found to be effective against Staphylococcus aureus ATCC 6538, Bacillus subtilis ATCC 6633, Klebsiella pneumoniae CCM 2318 and Mycobacterium smegmatis CCM 2067.