Tacrolimus is a calcineurin inhibitor recently approved in the US and throughout the EU for the prevention of allograft rejection in heart transplant recipients. It is commonly administered orally for long-term immunosuppression. The incidence of mild to severe acute rejection in the first 6 months following heart transplantation was significantly lower in tacrolimus recipients than in ciclosporin recipients (54% vs 66%) in a large, phase III trial conducted in Europe. A large, phase III trial conducted in the US did not show a significant difference between tacrolimus and ciclosporin in the incidence of severe rejection or haemodynamic compromise rejection requiring treatment within the first 6 months post-transplant (22% vs 32%), but did show a significant difference in the incidence at 1 year (23% vs 37%). In phase III trials, 1-year patient survival was similar between tacrolimus and ciclosporin recipients in the EU (93% vs 92%) and the US (95% vs 90%). Tacrolimus was shown to be effective in the prevention of rejection in paediatric and African American heart transplant recipients. The tolerability profile of tacrolimus in heart transplant recipients was broadly similar to that of ciclosporin, although tacrolimus was usually associated with lower incidences of post-transplant hypertension and dyslipidaemia.