The chemical structure of a novel thiopeptide antibiotic, glycothiohexide alpha (1), isolated from the fermentation broth of a ''Sebekia'' species was determined based on extensive 2D NMR studies, as well as, IR, UV, and mass spectral data. The chemical structure of glycothiohexide alpha is closely related to nosiheptide (3) and antibiotic S-54832A.