New isomers of clavine alkaloids with distinctively low chromatographic mobilities were isolated from the collection and mutant strains of Penicillium roquefortii Them 1906, in addition to alkaloids roquefortine, 3,12-dihydroroquefortine, isofumigaclavines A and B, festuclavine, and chanoclavine-I, which are characteristic of this species. It was demonstrated that the collection strain produces isomers of agroclavine and epoxyagroclavine, whereas the mutant strain synthesizes isomers of fumigaclavines A and B, festuclavine, and chanoclavine.