Previously we reported the isolation and structure of the chrysospermins as new peptaibol-type antifungal and antibacterial antibiotics from Apiocrea chrysosperma which display morphogenic activity against a small spectrum of fungal strains such as Phoma destructiva. Peptaibols are linear amphiphilic peptide antibiotics which are characterized by up to 20 amino acids linked in a linear order. They contain a high amount (up to 60%) of hydrophobic amino acids such as a-aminoisobutyric acid (Aib) and isovaline (Iva). The amino terminus is acetylated and the carboxyl terminus is reduced to the pertinent alcohols such as leucinol, phenylalaninol, valinol and tryptophanol. Agents such as alamethicin, hypelcins, emerimicins, paracelsins, chrysospermins and others owe their antimicrobial effects to the formation of ion-conducting channels within biological membranes. Our screening of other fungal strains for metabolites affecting fungal growth discovered Emericellopsis donezkii HKI 0059 as the producer of a new antifungal antibiotic which was given the name bergofungin. Here, we report the isolation, structure and biological properties of this new representative of the peptaibols. Bergofungin (1) is produced as the main component by Emericellopsis donezkii HKI 0059, but occasionally, small amounts of homologues were detected varying in the composition of amino acids.