Antimicrobial activity of Ganoderma lucidum mycelia was studied by the agar-well diffusion method. Methanol, acetone, chloroform and aqueous extracts of mycelia were analyzed for the antimicrobial activity against different Gram positive organisms and Gram negative organisms such as Staphylococcus aureus, Bacillus subtilis, Corynebacterium diphteriae, Escherichia coli, Proteus mirabilis, Klebsiella pneumoniae, Salmonella typhi and Pseudomonas P₁₈. All four extracts at concentration of 100 mg/ml showed maximum inhibition. It was observed that Gram positive organisms were more susceptible than Gram negative organisms.