The antibiotic Terramycin has been shown to have the structure I. Among the products of the metabolism of the actinomycete Streptomyces rimosus is Terramycin, a yellow crystalline amphoteric substance of the composition C22H24N2O9. The structure of Terramycin is of special interest in view of the marked activity of the metabolite against both gram-positive and gram-negative bacteria. In this communication, it is shown that Terramycin possesses the structure I.