A multiinstitutional randomized trial was undertaken comparing OKT3 with steroids for treatment of hepatic allograft rejection. All patients received baseline immunosuppression with Cyclosporine (CsA) and steroids. At the time of biopsy-confirmed rejection, up to 2 intravenous boluses (250-1000 mg) of methylprednisolone were initially administered. Twenty-eight patients who failed to respond were then randomly assigned to OKT3 or continued steroid therapy. Rescue therapy with the opposite treatment arm was added after 6 days if the primarily allocated protocol failed. Three of 13 patients assigned to the steroid group responded promptly, and continue with good function 7-12 months later. OKT3 rescue was required in 10 patients who failed to improve despite receiving up to 6 g of methylprednisolone (mean: 3.3 g/patient). One patient died of sepsis and hepatic failure. Rejection was reversed in 9 OKT3-rescue patients, 7 of whom are well 1-17 months later. In the OKT3 group, improved allograft function was observed within 72 hr in 11 of 15 patients. Two patients with inadequate response were successfully rescued with steroids; 1 patient underwent retransplantation; and 1 patient developed a biliary fistula that eventually resulted in sepsis and death. In summary, 23 of 28 hepatic recipients (82%) are alive with the original allograft 1-17 (mean 7.8) months after treatment for acute rejection. Another patient is alive 14 months following retransplantation. Eighteen (78%) of the survivors required OKT3 as initial (11) or rescue (7) therapy, whereas only 5 were successfully managed with steroids. OKT3 is superior to steroids for reversing liver allograft rejection and has greatly reduced the need for retransplantation even in recipients selected on the basis of having failed initial steroid therapy.