A hitherto undescr. mould metabolic product Fumigatin, C8H8O4, and its reduction product, C8H10O4, were isolated from cultures of A. }. grown on Raulin-Thom medium. Fumigatin is the quinone, 3-hydroxy-4-methoxy-2,5-toluquinone; its reduction product, the quinol, 3-hydroxy-4-methoxytoluquinol.