The structures of epohelmins A and B isolated as lanosterol synthase inhibitors from a fungal strain FKI-0929 were revised to be 1 alpha-hydroxy-3alpha-(4'-oxoundec-(5' E)-enyl)-pyrrolizidine and 1beta-hydroxy-3 alpha-(4'-oxoundec-(5 'E)-enyl)-pyrrolizidine, respectively, by comparison with spectral data of synthetic compounds.