<jats:title>Abstract</jats:title><jats:p>The antibacterial activity of the stem bark of <jats:italic>Erythrina caffra</jats:italic> Thunb. was investigated against different bacterial strains. The antibacterial activity was determined by a micro broth dilution assay. Antibacterial compounds were isolated and identified using a Bruker Avance III LPO NMR spectrometer. Four known flavonoids, abyssione‐V 4′‐<jats:italic>O</jats:italic>‐methyl ether, 6,8‐diprenylgenistein, alpinumisoflavone and burttinone, were isolated. All the compounds were active against both Gram‐negative and Gram‐positive bacteria. The minimum inhibitory concentration values obtained (MIC) ranged from 3.9 μg/mL to 125 μg/mL. This is the first report of antibacterial activity of burttinone and the isolation of these compounds from <jats:italic>E. caffra</jats:italic>. Copyright © 2010 John Wiley & Sons, Ltd.