Bithiazole-type antifungal products, cystothiazoles C-F (3-6), have been isolated from a culture broth of the myxobacterium Cystobacterfuscus as minor components. These are structurally related to cystothiazole A (1), which was isolated as a cytotoxic antibiotic from the same microorganism in our previous work. The structures of these compounds were elucidated by spectroscopic analyses. These new compounds inhibit the phytopathogenic fungus, Phytophthora capsici, but are less active than 1.