Fusaricidin A, a new depsipeptide antibiotic, was isolated from the culture broth of Bacillus polymyxa KT-8 obtained from the rhizosphere of garlic suffering from the basal rot caused by Fusarium oxysporum. The structure of fusaricidin A was determined by ID and 2D NMR and MS experiments coupled with amino acid analysis to be a hexadepsipeptide containing 15-guanidino-3-hydroxypentadecanoic acid as a side chain. The absolute configuration of each amino acid residue was determined by chiral HPLC. Fusaricidin A is active against fungi and Gram-positive bacteria.