Citridone D was isolated from the culture broth of Penicillium sp. FKI-1938 by solvent extraction, silica gel column chromatography and HPLC. The structure of citridone D was elucidated by spectroscopic analysis including NMR analysis. Citridone D was found to have a novel phenylfuropyridine skeleton different from those of other citridones. Citridone D potentiated miconazole activity against Candida albicans.