SUMMARY A study was conducted to evaluate effects of supplementation of a monocomponent protease on growth performance and protein utilization in Nicholas turkeys from 1 to 26 d of age fed corn-soy diets with reduced levels of CP and amino acids. Poults were placed into 40 batteries of 15 birds, and allocated to 5 treatments with 8 replicates each. A positive control diet [PC, 27.94% CP, 1.69 digestible Lys (DLys)] and a negative control diet (NC1; 24.21% CP, 1.46% DLys) were formulated. A second NC diet (NC2; 23.20% CP) was formulated with reduced CP and amino acids (AA) with expected improvements provided by a protease (1.014% CP, 0.024% DLys, 0.055% digestible TSAA, and 0.077% digestible Thr). The protease (75,000 PROT/g) was added at 200 mg/kg, at the expense of Celite (indigestible marker and filler) to create the NC1+P and NC2+P. Ileal contents were collected from all birds for apparent CP and AA digestibility determinations on d 26. A factorial arrangement of 2 × 2 + 1 was used (CP level × protease supplementation + PC). Turkeys fed the PC diet were 8.1% and 9.8% heavier (P < 0.05) compared with those fed the NC1 and NC2 diets and adding protease had no effect on BWG. Improvement in FCR (P < 0.05) were observed in birds fed the NC1 and NC2 diets. There was a main effect of protease (P < 0.0535) on FCR ratio, with birds fed diets with protease having better FCR than those without. There were no effects of the treatments on feed intake and carcass yield. Digestibility of CP was increased (P < 0.05) for turkeys fed the NC1+P diets in comparison to those fed the other diets, except the PC diet. Apparent digestibilities of Asp, Cys, Glu, Ile, Lys, Thr, and Val were affected by treatment, with birds fed the PC diet having the lowest digestibilities (P < 0.05). Poults fed protease-containing diets had better (main effect, P < 0.05) CP, Lys, and Cys digestibilities than those fed the diets without protease. Overall, the effects of the protease were limited but significant on FCR and specific AA digestibilities.