To examine the role of psychiatric diagnosis in the surgical outcome of pancreas transplantation, we studied candidates with type I diabetes mellitus. Eighty of 140 candidates underwent transplantation. Survival analysis found the extent of human leukocyte antigen-DR (HLA-DR) matching, two diagnoses, and patients’ perceived support from first-degree relatives to be related to duration of full-graft function. Lifetime diagnoses of tobacco use disorder (P = 0.029) and alcohol abuse/dependence (P = 0.006) were associated with less favorable outcomes; perceived support was associated with positive outcomes (P = 0.048). Subsequent analysis suggested that the four variables independently and directly affect outcome.