Trypsin inhibitors (TI) in soybeans influence protein utilization but wheth- er this is true for purified TI and if exogenous protease administration will ameliorate such effects are not known. Therefore, this study was designed to evaluate the effect of dietary mono-component protease on growth performance and nutrient utilization of broiler chickens fed diets containing purified TI. Soybean meal (SBM) was pre-analyzed for basal TI concentration (2,996 TIU/g SBM) and formulated to contain 1,033 TIU/g diet. Purified TI was added at 9,000 TIU/g diet. The diets were corn-SBM based, formulated to be nutritionally adequate and supplemented with phytase (1,000 FYT/kg). Using a 2 × 2 factorial arrangement, with two levels of dietary TI (1,033 or 10,033 TIU/g) and exogenous protease (0 or 15,000 PROT/kg), 320 chicks were allotted to 4 experimental diets, each containing 8 replicate cages and 10 birds per replicate. On d 7, 14 and 21 post hatching, protease supplementation improved the BW gain (P < 0.01) and feed efficiency (P < 0.05) of birds fed diets with added purified TI. On d 14 and 21 post-hatching, the relative weight of the pancreas increased (P < 0.05) with increasing dietary TI but reduced (P < 0.001) with protease supplementation. Apparent ileal digestibility of all amino acids decreased (P < 0.001) with added TI, and protease supplementation improved (P < 0.05) the ileal digestibility of all AA except methionine. Protease supplementation upregulated the mRNA expression of MUC-2 (P < 0.01) and SCL7A-2 (P < 0.05) in the jejunal mucosa, as TI concentration increased in the diets. The activities of trypsin and chymotrypsin in duodenal digesta were reduced (P < 0.05) with increased dietary TI but increased (P < 0.01) with protease supplementation. Birds fed diets supplemented with protease had longer villi (P < 0.05) and deeper crypts (P < 0.01) in the jejunal tissue.