Cyclosporine (CsA) nephrotoxicity is an important problem in renal transplant recipients, which can influence long-term graft survival. The safety of conversion from CsA to azathioprine (AZA) remains controversial and can result in higher incidence of acute rejection. Mycophenolate mofetil (MMF) is a new immunosuppressive agent superior to AZA in the prevention of acute rejection. Five patients with cyclosporine nephrotoxicity were converted from CsA/AZA/prednisolon to MMF/prednisolon protocol. All patients had low immunological risk and 4 out of 5 patients received antithymocyte globulin before conversion as the induction therapy or as the treatment for acute rejection. Mean follow-up after conversion was 16.8 months (range 4-32 months). No patient experienced acute rejection during follow-up period. The mean serum creatinine concentration decreased from 219 +/- 44.18 (range 168-280) to 122.6 +/- 48.02 mumol/l (range 72-187 mumol/l) (p = 0.002). Arterial hypertension improved after CsA withdrawal in 20% of patients. We have concluded that, in selected patients with cyclosporine nephrotoxicity, CsA withdrawal with concomitant use of MMF is safe and effective in the improvement of graft function and arterial hypertension.