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Abstract: A feeding trial was conducted to determine the optimum dietary protein requirement of a new Japanese strain of juvenile Chinese soft-shell turtle, Pelodiscus sinensis. Five iso-energetic diets were formulated to contain graded protein levels of 340, 370, 400, 430 or 460gkg−1 diet and fed to triplicate groups of turtles (mean initial weight, 3.70±0.05g) for eight weeks. The turtles were reared in 350-L indoor plastic containers (15 turtles/container) provided with aerated freshwater. For each graded increase of dietary protein up to 430gkg−1 diet, growth performance of the soft-shell turtles increased significantly. No further growth increase was observed beyond this dietary protein level. The highest feed efficiency and protein productive value were observed in P. sinensis fed the 430gproteinkg−1 diet. In general, the apparent digestibility coefficients (ADC) of dry matter, crude protein and gross energy increased significantly with increasing dietary protein levels. No significant differences were observed in the ADC of crude lipid among all experimental groups. Turtle whole-body protein content increased significantly from 15.2% to 16.8% with a corresponding decrease in moisture content (75.5% to 74.2%) when fed increasing dietary protein levels. The lowest concentrations of serum protein and cholesterol were observed in turtles fed 340 or 460gproteinkg−1 diet. Aspartate transaminase activity in turtles fed 340gproteinkg−1 diet was significantly higher compared to those fed 400 or 430gproteinkg−1 diet. Broken-line regression analysis indicated that juvenile P. sinensis (Japanese strain) requires 422.0gproteinkg−1 diet for optimum growth. [Copyright &y& Elsevier]