Despite the widespread use of potent immunosuppressive drugs, such as cyclosporin A and mycophenolate mofetil, ongoing and recurrent cellular rejection remain a common problem after heart transplantation. We aimed to describe the long-term effects of conversion from cyclosporine A to tacrolimus in patients with ongoing and recurrent cellular rejection. This was a single-centre retrospective analysis of 17 heart transplant recipients who were switched from cyclosporine A to tacrolimus due to ongoing (5 patients) or recurrent cellular rejection (12 patients). We studied long-term efficacy and safety of this approach. 167 endomyocardial biopsies were performed during a mean follow-up of 69.1 +/- 12.7 months. Thirteen biopsies (7.8%) in eight patients (47%) revealed higher grades of acute cellular rejection (Banff 2). However, they were not hemodynamically significant and did not require intravenous antirejection therapy. The mean rejection score was reduced significantly. Conversion to tacrolimus was tolerated in 82% pts without any significant side effects during a long-term follow-up. In conclusion, the conversion to tacrolimus in heart transplant recipients with ongoing or recurrent acute cellular rejection was safe and effective also during a long-term follow-up.