The aim of this pilot study was to investigate whether de novo calcineurin-inhibitor-free immunosuppression after cardiac transplantation is efficacious and can prevent post-operative renal impairment. Eight patients were treated by combining trough level adjusted sirolimus and mycophenolate mofetil; corticosteroids were given for the first 6 post-operative months only. Survival data, acute rejection episodes and adverse events with a special emphasis on renal impairment, myelosuppression, hypercholesterolemia, hypertriglyceridemia and infections, were recorded. With a follow-up of 3-12 months, patient survival was 100% and freedom from rejection 75%. The mean creatinine levels initially decreased and remained stable thereafter. A moderate myelosuppressive effect did not necessitate dose reduction of immunosuppressants, intermittently elevated cholesterol- and triglyceride levels decreased over time. Most frequent adverse events were pericardial effusions and peripheral edema. Complete abandonment of calcineurin inhibitor therapy by de novo use of the combination sirolimus/mycophenolate mofetil resulted in low rejection rate and avoidance of renal impairment, but should not be used without further evaluation of potential complications in a lager setting.