In the course of screening for new antibiotics active against methicillin-resistant Staphylococcus aureus, we isolated an antibacterial metabolite from the culture broth of a basidiomycete, which was named epicorazine C (1). Spectroscopic analysis revealed that 1 was a member of the epidithiopiperazinedione group, represented by epicorazine A (2), B (3)^3) and 3822-A (4)4), which were isolated also from fermentations of the same culture (Fig.1). In this case, it was the first isolation of epicorazines from a basidiomycete. Antibiotic 1 has already been mentioned in a previous paper as derivative of 45\ but it was not named. No details of biological and physicochemical data of 1 have so far been published although the congeners 2 and 3 were well known in early times. Antibiotic 1 inhibited growth of Gram-positive bacteria including methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant Enterococcus faecalis (VRE) as well as Candida albicans. The isolation, structure determination and biological properties of 1 will be described in the following.