α- and β-luffins were easily and quickly isolated and purified from seeds of Luffa cylindrica by using an improved procedure that involved ammonium suifate preciptation, ion exchange chromatography on S Sepharose Fast Flow and gel filtration on Sephadex G-75.α-and β-luffins were basic proteins with isoelectric points of about 10, with molecular weight of 28 000 and 29 000, respectively, as judged by SDS-PAGE. Inhibitory activities of α-luffin and β-luffin on cell-free protein synthesis were stronger than that of any known type-1 RIPs，with ID₅₀ 10μg/L and 50μg/L, respectively.