Cardiologists caring for heart transplant recipients must be familiar with the pharmacology, drug interactions, and drug toxicity of those agents used extensively in clinical practice (cyclosporine, prednisone, azathioprine, polyclonal and monoclonal anti-T-cell agents) and the newer treatments [methotrexate, FK-506, rapamycin, mycopheno-late mofetil (RS61443), deoxyspergualin, anti-CD4 monoclonal antibodies, total lymphoid irradiation, and photophoresis]. Another important aspect of medical follow-up is the detection, differential diagnosis, and treatment of allograft dysfunction. Hemodynamic abnormalities that occur as a result of rejection or a direct drug effect must be differentiated from physiologic changes. Cardiac allograft vasculopathy is the primary impediment to the long-term survival of heart transplant recipients. Immunopathogenesis, prevention, early detection, and treatment of allograft vasculopathy should be the major focus of heart transplantation research.