Twenty cadaveric renal transplant patients (mean age 12.5 +/- 4.8 years) received 14 days (mean 13.0 +/- 2.8 days) of OKT3 (mean dose 0.16 +/- 0.09 mg/kg) along with prednisone 0.5 mg/kg per day, azathioprine 2 mg/kg per day and cyclosporine 5 mg/kg per day which was increased to obtain therapeutic levels before the discontinuation of OKT3. Actuarial patient and graft survival were 100% and 50%, respectively, at both 1 and 5 years. Four children lost their grafts within the first 48 h. One loss was technical in origin, the remaining 3 had pathological evidence of vascular thrombosis. Of the remaining 16 children, 12 (75%) experienced rejection episodes within the first 2 months post transplant (mean 27 +/- 15 days). Successful reversal of early rejection episodes was achieved in 11 of 12 patients. Clinically significant cytomegalovirus infection occurred in 4 patients and resulted in graft loss in 2 patients. Circulating OKT3 levels ranging from 1,000 to 32,000 ng/ml were seen in all patients within the first 48 h. There was a rapid and total depletion of circulating CD3-positive lymphocytes in all patients. Anti-isotypic and anti-idiotypic OKT3 antibodies were assessed by enzyme-linked immunosorbent assay (ELISA), and blocking anti-idiotypic antibodies were detected by immunofluorescence inhibition assay. Positive OKT3 antibody titers were detected in 11 children by ELISA and 10 children by immunofluorescence inhibition assay.(ABSTRACT TRUNCATED AT 250 WORDS)