Plant protease inhibitors (PIs) are very important for their defensive function against plant pathogens and predators. In present work trypsin and chymotrypsin inhibitors (PIs) from gum of one tree about seven species, Azadirachta indica, Acacia leucophloea, Acacia nilotica, Terminalia spp., Anogeissus latifolia, Mangifera indica and Moringa oleofera are studied. Protease inhibitory activity in gum extract was detected by dot blot assay. PI bands were resolved on electrophoresis gel and detected by Gel X-ray film contact print technique (GXCP). PIs from gum extracts were purified by gel filtration (Sephadex G-75). Among all gum extracts studied, the gum extract from Acacia leucophloea showed highest number of trypsin and chymotrypsin inhibitors. One PI from the Acacia leucophloea of 97.00kDa was purified and characterized. Purified PI was not destroyed by heat treatments up to 70oC, but lost its activity when incubated at 80°C, showing moderate thermo stability.