The structure of glomosporin, an antifungal antibiotic, was elucidated by NMR and MS spectroscopic studies. Glomosporin is a novel cyclic depsipeptide with an amino acid sequence Ser-Ala-Asp-Asn-Asn-Ser-Thr, and a 3,4-dihydroxy-4-methylhexadecanoic acid side chain.