Three new beauvericins, designated beauvericins D, E and F, were isolated along with known beauvericin and beauvericin A, from the culture of Beauveria sp. FKI-1366 by solvent extraction, ODS column chromatography and HPLC. These compounds potentiate miconazole activity against not only wild Candida albicans but also fluconazole resistant C. albicans. Beauvericins D and E decreased the IC50 value of miconazole against fluconazole resistant C. albicans from 1.3μM to 0.25 and 0.31μM, respectively. In this paper, we describe the taxonomy of the producing fungus, fermentation, isolation and miconazole-potentiating activity of these beauvericins.