Pancreas transplantation is an appropriate form of treatment for a highly selected group of patients with diabetes who have the most severe complications of this disease. The largest group of patients are those who have developed chronic renal failure secondary to diabetes; these patients undergo simultaneous pancreas and kidney transplantation. The other group of patients comprises those with diabetes which is extremely difficult to control, particularly because of episodes of severe hypoglycemia which occur without warning. Pancreas transplantation is a major surgical procedure with substantial attendant risks, which have to be balanced against the benefits for every patient. However, there is good evidence that patients with successful pancreas transplants have an extended life expectancy compared to those who undergo a kidney transplant alone for diabetic renal failure. Other evidence is accumulating to show benefit with respect to the secondary complications of diabetes, particularly retinopathy and nephropathy. Currently the two major limitations on pancreas transplantation are the risk of early postoperative pancreatitis, and the long-term difficulty of monitoring the pancreas.