New Cyclopeptides fromTrichoderma polysporum(LINK EXPERS.) RIFAI: Cyclosporins B, D and ECyclosporins represent a new group of biologically active metabolites produced byTrichoderma polysporum(LINK EXPERS.) RIFAIand other fungi imperfecti. The structures of the main components, cyclosporins A (1) and C(3) have been determined as neutral cyclic oligopeptides composed of 11 amino acids, among them a new C9‐amino acid [2–4]. In addition, three minor metabolites, cyclosporins B, D and E, have now been isolated and characterized. Chemical investigation, spectroscopic evidence and X‐ray analysis led to the structural formulae of cyclosporins B(2)and D(4). Both compounds have the same sequence of amino acids as cyclosporin A(1), with the exception ofL‐α‐aminobutyric acid, replaced in cyclosporin B(2)byL‐alanine and in cyclosporin D(4)byL‐valine, respectively. Cyclosporins undergo a characteristic intramolecularN,O‐acyl migration to furnish the corresponding basic isocompounds. The antifungal activities of cyclospor