Six transplantations of the liver were performed over a period of six years in five adult patients with Type I diabetes mellitus (DM). The diabetic group included two males and three females with a mean age of 36 years and a mean duration of DM of 20 years. Primary diseases of the liver included two instances of primary biliary cirrhosis, two instances of sclerosing cholangitis and one instance of autoimmune chronic hepatitis. Three patients also received a simultaneous whole organ pancreatic transplant. All patients were managed with cyclosporine and prednisone immunosuppression with selective OKT3 induction. Patient and hepatic allograft survival rates were 80 and 67 percent, respectively, after a mean follow-up period of 4.7 years. One of the three pancreatic grafts was successful and resulted in euglycemia for two years. Three patients have subsequently undergone successful renal transplantation at one, two and one-half, and six and one-half years after hepatic transplantation. Although transplantation of the liver can be performed safely in carefully selected patients with Type I DM, these patients are still at risk for the development of progressive nephropathy. Renal transplantation is an acceptable therapeutic alternative when this occurs.