Minnamide A is a lipopeptide with a unique repeating structure consisting of hydroxy and proposed β-branched methyl groups. The absolute configuration of minnamide A was determined by a combination of chemical degradation, chiral HPLC analyses, and synthetic methods. Minnamide A showed growth-inhibitory activity toward HeLa cells with an IC50 value of 0.17 μM and rapidly induced cell death at a concentration of 2 μM. Minnamide A induced the copper-mediated accumulation of reactive oxygen species.