Beyond the immediate post-transplant period, physicians are often reluctant to use anti-lymphocyte preparations to treat episodes of acute renal functional deterioration attributable to acute rejection. This is due to the perception that such episodes are less likely to be reversible, and to concern regarding the potential adverse effects of anti-lymphocyte antibodies, including opportunistic infections, lymphoproliferative disorders, and the development of human anti-mouse antibodies. Records were reviewed for all 365 renal transplants performed in 267 patients at our center from 1971 to 1996. Anti-lymphocyte antibodies were used in an attempt to reverse 6 episodes of corticosteroid-resistant acute rejection in 5 children at a mean interval of 24.5 months following transplantation. The mean serum creatinine at initiation of therapy with the anti-lymphocyte agents was 2.9 mg/dl. Following treatment, the mean serum creatinine decreased to 1.3 mg/dl (P=0.03, Student's t-test). Two patients developed uncomplicated opportunistic infections after completion of anti-lymphocyte therapy; none have developed lymphoproliferative disorders or antibodies to OKT3. We conclude that in the correct clinical setting with corticosteroid-resistant acute rejection, the use of anti-lymphocyte antibodies should not be withheld solely on the basis of length of time since transplantation.