The aim of this study was to evaluate the impact of sirolimus and cyclosporine (CsA) combined therapy on the incidence and duration of delayed graft function (DGF), and the impact of the latter on 1-year graft function. The study entailed 23 cadaveric renal recipients treated with sirolimus-CsA-prednisone regimen (sirolimus group). The reference group entailed 23 patients treated with CsA-azathioprine-prednisone. In the sirolimus group the frequency of DGF was 39% and was essentially the same as in reference group (34.8%). The duration of DGF was significantly longer in SRL group and lasted 21.2 +/- 12.2 days versus 6.8 +/- 2.5 in reference group (P = .004). Serum creatinine level decreased below 3.0 mg/dL after 36 +/- 22 days in sirolimus group versus 16.8 +/- 6 days in reference group (P < .04). Cold ischemia was slightly longer and donors were older in DGF patients in both groups. Sirolimus dose during first month was higher in DGF patients (3.5 versus 2.6 mg), whereas level of CsA was lower (230 versus 310 ng/mL). Biopsy-proven acute rejection (AR) occurred in most of DGF patients and during the DGF period. Serum creatinine level at the 12th month posttransplant was higher in DGF versus non-DGF patients (2.0 +/- 0.5 versus 1.5 +/- 0.4 mg/dL). One-year patient and graft survival was 100% in sirolimus group and 100% and 95% in reference group. In conclusion, sirolimus significantly retards the recovery from posttransplant renal failure; however, it does not increase the incidence of DGF. Patients who suffered from posttransplant acute renal failure had worse renal function at 1 year after transplantation, independent of the treatment protocol.