Proteinase inhibitors (PIs) are small proteins that are quite common in nature. PIs are present in multiple forms in numerous tissues of animals and plants as well as in microorganisms. Serine proteinase inhibitors are widespread in the plant kingdom. The present study was at investigating the biochemical properties of protease Lavatera cashmeriane seeds. Four protease inhibitors LC-pi I, LC-pi II, LC-pi III and LC-pi IV were purified from the seeds of Lavatera cashmeriane by ammonium sulphate precipitation and ion-exchange chromatography on DEAE-cellulose column. All were strong inhibitors of trypsin, chymotrypsin and elastase. The molecular weight of LC-pi I, LC-pi II, LC-pi III, and LC-pi IV was found to be 20.89, 14.12, 16.78 and 7.94kDa respectively by gel filtration chromatography and 10, 14, 16 and 7kDa respectively by SDS-PAGE. The SDS-PAGE revealed that LC-pi I is constituted of two subunits of 10,000 Da each. The optimum temperature for the inhibitors was found to be 30?C for all inhibitors. LC-pi I showed strong antibacterial activity against Klebsiella pnuemoniea, and Pseudomonas aeruginosa but was less active against E.coli.