Oryzoxymycin (I), an antibiotic produced by Streptomyces venezuelae var. oryzoxymyceticus, is unstable and easily dimerizes to an inactive crystalline product. Structural study of this product led to the conclusion that the structure of oryzoxymycin is D-2-[(+)-6-amino-trans-5-hydroxy-1, 3-cyclohexadienel-carbonyloxy]-propionic acid: