Festuclavine, previously isolated from saprophytic cultures of strains of ergot (Claviceps) found on certain grasses, has been found in cultures of Aspergillus fumigutus Fres. Two new alkaloids, also of the clavine type, have been isolated and characterised, and for them the names fumigaclavine A and B are proposed. Fumigaclavine B, which is deacetylfumigaclavine A, has also been found in Rhizopus arrhizus Fischer.