The introduction of cyclosporine revolutionized the practice of immunosuppression for solid organ transplant recipients, and has resulted in a significant increase in survival. While CNI use has been the mainstay of immunosuppressive therapy in pediatric heart transplantation, CNIs have been associated with an increased risk of nephropathy leading to significant morbidity and mortality. We evaluated the effect on renal function of a CNI minimization protocol using SRL in pediatric heart transplant patients with CNI induced renal insufficiency. An IRB approved retrospective chart review and case control study was performed. There were 20 patients identified with renal insufficiency who had been converted to SRL (target 5-8 ng/mL) and cyclosporine (target 50-75 vs. 125-150 ng/mL). Renal insufficiency was defined as isotopic (Indium 111 DTPA) GFR <60 mL/min per 1.73 m(2) or sCr >1 mg/dL. Outcome variables evaluated were GFR and sCr at time of conversion and at two yr post conversion. Comparison was made with case control subjects matched for age at Tx, time from Tx to conversion, and initial GFR. The median age at Tx = 81 days (S.D. ±26), median time of conversion after Tx = 10 yrs (s.d. ±0.65). Self-limited/treatable side effects included hypercholesterolemia (10), neutropenia (6), aphthous ulcer (3), edema (2), anemia (2), and tremor (1). One patient rejected in the two yr prior to conversion, and one patient had two rejection episodes following conversion. GFR at conversion for study group was 51 ± 14 vs. 60 ± 2 at two yr, p = 0.018. GFR at inclusion for control group was 56 ± 20 vs. 53 ± 21, p = 0.253. This report demonstrates that minimizing CNI exposure by addition of SRL to the immunosuppressant regimen in pediatric heart transplant recipients result in improved renal function in comparison to historically managed patients. Furthermore, immunotherapy with SRL and lower-dose CNI can effectively prevent rejection with an acceptable side-effect profile.