Pancreatic growth was studied after partial resection of the normal-sized pancreas in rats fed heated soya flour (HSF) or the enlarged gland in rats fed raw soya flour (RSF). Resection involved the removal of the splenic and gastric segments and in both the normal and enlarged gland this represents a loss of approximately 55% of total pancreatic mass. After partial resection animals were either continued on these preresected diets or changed to the alternative diets. For at least the first 8 days after resection, in all conditions studied, there was a significant increase in DNA synthesis in the pancreas, involving both parenchymal and nonparenchymal cells as shown by autoradiography. The increased cell turnover was not associated with any increase in total DNA content of the gland, indicating that the increase paralleled cell loss in response to injury caused by the surgery. By 160 days after resection of the normal pancreas, RSF feeding caused both hypertrophy and hyperplasia of the remnant, but after partial resection of the enlarged gland, growth was limited to hypertrophy. These results suggest that the pancreas has a limited capacity for additional growth after that initially caused by RSF.