Summary When defatted raw soybean meal was fed to weanling female rats for 192 days, pancreatic hypertrophy, reduced feed efficiency, and decreased body weight gains were observed. Pancreas enlargement was also observed when adult male rats were fed the raw soybean meal containing diet for the same period. The pancreatic hypertrophy in rats ingesting raw soybean meal for 38 days was reversed when the rats were switched to the control diet for 154 days. Pancreatic tissues, which had been hypertrophied for more than 6 months, showed no histopathological damage.