Background. Chronic cyclosporine (CsA) nephropathy, which has been unequivocally documented in recipients of heart, heart-lung, liver, or bone marrow transplants, as well as in nontransplant situations, usually results in a progressive deterioration of renal function, In this study, we assessed the potential reversibility of chronic CsA nephropathy in renal transplant recipients, Patients and Methods, Twenty-three renal transplant patients with biopsy-proven CsA nephropathy associated with long-term CsA administration (27+/-4 months) were followed up for more than 2 years after CsA reduction (18/23 patients) or withdrawal (5/23 patients) and addition of azathioprine, Changes in effective renal plasma flow and glomerular filtration rate were assessed before and 2 years after CsA reduction, whereas serum creatinine, proteinuria, blood pressure, and CsA concentrations were monitored up to 5 years, Results, At a-year follow-up, glomerular filtration rate increased from 40+/-3 to 47+/-4 (P<0.05) and effective renal plasma flow from 217+/-23 to 244+/-24 ml/min/1.73 m(2) (NS). Mean arterial pressure significantly decreased from 98.7+/-2.9 to 93.1+/-2.7 mmHg (P<0.05). There was no significant change in renal vascular resistance, filtration fraction, or albumin excretion, A significant decrease in serum creatinine was also observed during the whole follow-up (73+/-6.5 months), CsA reduction was followed by only one episode of acute reversible rejection; chronic rejection developed in three patients 2 years or later after CsA reduction, Conclusions, These data suggest that CsA nephropathy participates in graft dysfunction in a small group of renal transplant recipients, In addition, graft dysfunction may be reversible when CsA dosage is reduced early after diagnosis of chronic CsA nephropathy.