Carcinoid tumors are endocrinologic malignancies often associated with a characteristic syndrome—the malignant carcinoid syndrome. Cardiovascular manifestations of this rare illness result from unique pathophysiologic characteristics, are associated with poor prognosis, and are difficult to treat medically. The hemodynamic consequences of this disease present unique management problems perioperatively. New pharmacologic and surgical therapies for malignant carcinoids have improved quality of life for patients to the extent that carcinoid heart disease now has more impact on morbidity and mortality rates. Cardiologists may be called on to diagnose and treat this rare cardiac disease. We review, for consulting cardiologists, the pathophysiologic characteristics, cardiovascular manifestations, and management of this disease. (Am Heart J 1997;134:693-702.)