Clinical studies suggest that carcinoma of the pancreas may be more common in patients with chronic diabetes mellitus. To examine the effect of diabetes on growth of pancreatic carcinoma, 5 X 10(5) cultured hamster H2T pancreatic carcinoma cells were implanted into the cheek pouches of streptozocin-diabetic and nondiabetic Syrian hamsters. Tumor size and weight and total tumor DNA content 22 days after implantation were significantly greater in animals with diabetes. Thus streptozocin diabetes appears to promote the growth of pancreatic carcinoma cells in the hamster.