The purpose of this study was to assess the safety and efficacy of the insulin sensitizer rosiglitazone in patients with new-onset diabetes mellitus (NODM) after renal transplantation. Twenty-two patients with NODM after renal transplantation were selected to receive rosiglitazone therapy. All patients received prednisone, 15 patients were treated with tacrolimus and seven patients received cyclosporine A. For 16 of the 22 patients treatment with rosiglitazone therapy was successful and mean fasting blood glucose decreased from 182 +/- 17 to 127 +/- 7 mg/dl. Six patients were not treated successfully with rosiglitazone alone, one patient needed a second oral antidiabetic agent and four patients insulin therapy. In one patient rosiglitazone was stopped because of edema after 5 days. There were no changes either in serum creatinine concentrations, or cyclosporine and tacrolimus blood levels respectively. Treatment with rosiglitazone appears to be safe and effective in patients with NODM after renal transplantation.