Leucinostatin, a peptide antibiotic, was separated by silica gel and alumina column chromatography into two related components designated as leucinostatin A hydrochloride (C61H111-N11O13.HCl) and leucinostatin B hydrochloride (C61H109N11O13.HCl). Physico-chemical as well as biological properties of the two separated components were analyzed. These properties pointed to closely resembling chemical structures.