A 15-kDa antifungal protein, designated ganodermin, was isolated from the medical mushroom Ganoderma lucidum. The isolation procedure utilized chromatography on DEAE-cellulose, Affi-gel blue gel, CM-Sepharose and Superdex 75. Ganodermin was unadsorbed on DEAE-cellulose and adsorbed on Affi-gel blue gel and CM-Sepharose. Ganodermin inhibited the mycelial growth of Botrytis cinerea, Fusarium oxysporum and Physalospora piricola with an IC50 value of 15.2 microM, 12.4 microM and 18.1 microM, respectively. It was devoid of hemagglutinating, deoxyribonuclease, ribonuclease and protease inhibitory activities.