The aim of this study was to retrospectively evaluate safety and feasibility of sirolimus (SRL) monotherapy in kidney transplant recipients. Patients older than 18 years, with monotherapy prescribed for more than 1 month and at least 6 months of follow-up were included. We analysed the data from 138 patients. Mean time period between transplantation and start of monotherapy was 6.5 +/- 4.1 years.The most frequent reason was minimization of immunosuppression followed by malignancy. Acute rejection rate was 1.4% at 12 months (two episodes). Graft and patient survival were 94.2% and 97.1% respectively. Mean follow-up after initiation of monotherapy was 29.4 months. Two patients died as a result of cardiovascular diseases and two because of malignancy. Percentage of withdrawal from monotherapy was 14%. SRL trough levels were 10.2 +/- 2.3 ng/ml at baseline and 9.6 6 +/- 3.3 ng/ml at 12 months. Mean glomerular filtration rate was 48.4 ml/min/1.73 m(2) at baseline and 47.7 ml/min/1.73 m(2) at 12 months. Proteinuria was 499.7 mg/24 h at baseline and 543 +/- 794 mg/24 h at 12 months. No significant changes in lipids, glucose, or hemoglobin occurred, although the percentage of patients treated with statins and Epo increased at the end of the follow-up. SRL monotherapy is suitable as long-term immunosuppression in selected patients with no significantly increased risk of late acute rejection.