Purpose Despite improvements in immunosuppressive therapy, chronic rejection, renal toxicity and malignancy are the major obstacles for long-term success after heart transplantation. We performed the worldwide first pilot-trial to evaluate the efficacy and safety of a de-novo calcineurin-inhibitor (CNI)-free immunosuppressive protocol. Between May 2003 and April 2005, 15 de-novo cardiac transplant recipients were assigned to receive sirolimus, mycophenolate mofetil and steroids. Antilymphocyte induction was given for 5 days; steroids were withdrawn after 6 months. A total of six of 15 patients received cytomegalovirus (CMV)-prophylaxis for high-risk CMV constellation (R(-)/D(+)). Results Survival at 1 and 5 years was 87.5%. Freedom from biopsy-proven rejection was 71.3% at 1 year and 59.4% at 5 years. Freedom from angiographically detectable vasculopathy was 100% after 5 years and only one CMV infection occurred. Mean serum creatinine was 1.43 +/- 0.31 mg/dl prior to heart transplantation (HTx), 1.29 +/- 0.56 mg/dl at 1 year and 1.23 +/- 0.53 mg/dl at 5 years. Cholesterol was 203 +/- 32 mg/dl at 1 year and 199 +/- 40 mg/dl at 5 years despite statins, and hypertriglyceridaemia (223 +/- 97 mg/dl) persisted after 5 years. No new-onset diabetes occurred. Surgical interventions for pericardial effusions were necessary in five patients. Nine patients discontinued sirolimus treatment temporarily because of side-effects (four acute rejections, three delayed wound healing and two gastrointestinal toxicity), all nine patients were reintroduced to sirolimus after the side-effects resolved. Summary CNI-free immunosuppression is possible and long-term results are favourable for survival, malignancy, renal function, CMV infections and vasculopathy. On the other hand, de-novo CNI-free immunosuppression after HTx is less efficacious in preventing acute rejection and has an inferior side-effect profile.