Orthoclone (OKT3, Ortho Biotech Inc, USA) monoclonal antilymphocyte antibody is a powerful T-cell-specific immunosuppressive agent. OKT3 has been used for induction therapy in kidney and liver transplantation, as well as to treat acute or steroid-resistant acute rejection episodes (ARE). This study was a retrospective analysis of 43 renal transplant recipients who developed steroid-resistant ARE and were treated with OKT3 between September 1994 and June 2004. The recipients were 36 men and 7 women of mean age 32.7 +/- 11.6 years (range, 19 to 48 years). The mean time from transplantation to OKT3 treatment was 7.2 +/- 6.7 months. Thirty-four episodes (79.1%) responded to OKT3 therapy with improved graft function, but the remaining 9 (20.9%) grafts did not respond. Among the 34 OKT3 responders, the mean serum creatinine decreased from 3.96 +/- 2.5 mg/dL to 2.45 +/- 1.77 mg/dL after treatment. Eleven (25.6%) of the 43 patients experienced minor side effects: fever, dyspnea, tachycardia, bradycardia. One patient (2.3%) developed acute pulmonary edema; one (2.3%), cytomegalovirus infection; and eight (18.6%), bacterial infections. The 1-, 3-, and 5-year graft survival rates for the 34 patients who responded to OKT3 therapy were 96%, 93%, and 85%, respectively. All patients are currently alive. The results indicate that OKT3 is a safe, effective treatment choice for steroid-resistant ARE in kidney transplantation.