Tacrolimus is an effective immunosuppressant in the rescue of liver allograft patients in whom conventional immunosuppression failed. Efficacy and safety were examined in a multicenter trial of liver transplant recipients converted to tacrolimus because of rejection despite cyclosporine (CyA) therapy or intolerance to CyA. Six hundred seventy-seven patients were enrolled onto the study; 475 patients for rejection, 197 patients for intolerance, and 5 patients treated compassionately. The mean daily dose of tacrolimus was less in the intolerance (Int) patients throughout the study: 0.22 versus 0.17 mg/kg at 1 week and 0.14 versus 0.11 mg/kg at 24 months in rejection (Rej) and Int patients, respectively. Mean blood levels paralleled dosing in both groups, but were greater in the Rej patients (10.7 v 8.3 ng/mL at 18 months). Kaplan-Meier estimates of patient and graft survival were similar in the two groups. Patient survival rates were 80.1% and 81.5%, and graft survival rates were 72.7% and 73.9% at 24 months in the Rej and Int patients, respectively. Most adverse events occurred with a similar incidence in the two groups. Those with a 4% or greater incidence were fever, viral hepatitis, and pneumonia. The incidence of sepsis, gastrointestinal hemorrhage, kidney failure, and convulsion was greater in the Int group. The incidence of abnormal liver function test results, hyperglycemia, headache, and abnormal kidney function was greater in the Rej group. Mean liver function test results decreased with time postrescue in both groups. Mean serum creatinine level increased from baseline to 18 months postrescue in both groups (1.44 to 1.51 mg/dL for Int patients, 1.14 to 1.48 mg/dL for Rej patients). We conclude tacrolimus is safe and effective rescue in liver transplant recipients with rejection or CyA intolerance.