Staphylococcal enterotoxin E has been purified by a combination of Red-A ligand chromatography and Mono-S (cation-exchange) chromatography. Commencing with 30 litres of fermenter-grown culture the method has been used to purify 17 mg of toxin, giving a purification yield of around 40%. The purity of the toxin was over 98% when analysed by sodium dodecyl sulphate-polyacrylamide gel electrophoresis, but demonstrated three isoelectric forms by isoelectric focusing, with pl values of 7.6, 7.4, and 7.0. This method adds to the versatility of the Red-A matrix system which can also be used for the purification of staphylococcal enterotoxins A, B, and C2.