Rapamycin powerfully inhibits the progression of antigen-activated T cells through the cell cycle. In animal heart transplantation models, rapamycin therapy has been associated with profound immunosuppressive effects on host humoral and cellular responses. In consequence, further studies have been conducted to evaluate the efficiency of rapamycin in preventing acute heart allograft rejection, treating refractory acute heart allograft rejection, inducing transplantation tolerance, and preventing and treating transplant coronary artery disease. The results of these studies indicated that rapamycin can effectively prevent acute graft rejection and inhibit refractory acute graft rejection in heart transplant recipients by exerting potent immunosuppressive and antiproliferative effects without adversely affecting renal function. This supports the use of rapamycin therapy in heart transplant recipients, especially in those with renal dysfunction, for whom treatment with calcineurin inhibitors is contraindicated. Rapamycin may also halt and even reverse the progression of cardiac allograft vasculopathy, which warrants further clinical trials in humans. Finally, rapamycin may be able to induce transplantation tolerance, thus making it one of the most promising modalities for improving the long-term survival of heart transplant recipients.