A multicenter, prospective, open-label trial was performed to assess the efficacy and safety of tacrolimus for primary immunosuppression in renal transplantation. Twenty patients were evaluated after receiving cadaveric and living, related or unrelated kidney transplants and were monitored for 6 months for patient and graft survival, incidence of acute rejection, and incidence of adverse events. Tacrolimus at a final mean dose of 0.11 mg/kg per day was 100% effective in preventing acute rejection in this Mexican population. Treatment was associated with a low incidence (10%) of posttransplant diabetes mellitus.