High-moisture extrusion of soy protein isolate generates a highly palatable meat substitute. No systematic evaluation of the nutritional quality of soy processed in this manner has been performed. This study compared the growth rate of male and female mice fed diets containing soy protein isolate without extrusion or with high-moisture extrusion. Other measures of overall growth and animal health were examined. Minor differences in the parameters were observed. Overall, the extruded soy protein was equally nutritious as the unextruded soy protein for the animals. Hence, high-moisture extrusion may be considered a useful method to generate high-quality protein foods. A longer term feeding trial may be recommended to further define the nutritional adequacy of this protein.