The efficacy of cyclosporine is documented, but it has side effects that are troublesome. Another compound, OG37-325, has been identified that appears to have similar efficacy, but less nephrotoxicity. This study was designed to address the benefits and toxicities of cyclosporine and OG37-325 in a prospective, randomized, double-blinded trial in cadaveric renal transplant recipients. The preliminary results demonstrate similar outcomes in terms of patient and graft survival, but suggest less nephrotoxicity in the OG37-325-treated patients. Longer follow-up will delineate the utility of OG37-325 in solid-organ transplantation.