Lipiarmycin, a metabolite of Actinoplanes deccanensis nov. sp. (PARENTI et al.), has been isolated in pure form. It has a molecular formula C52 CONGRUENT TO 54H74 CONGRUENT TO 76Cl2O19, (M.W. = 1,073 CONGRUENT TO 1,099). From its chemical and physico-chemical characteristics, lipiarmycin can be considered a new antibiotic. Lipiarmycin is highly active against Gram-positive bacteria, including strains resistant to the medically important antibiotics and protects mice experimentally infected with Streptococcus haemolyticus. Liparmycin inhibits growth of susceptible bacteria by interfering with RNA synthesis.