Orthotopic heart transplantation is contraindicated in patients with pulmonary hypertension and an elevated pulmonary vascular resistance. In an attempt to make otherwise unacceptable patients possible candidates for heart transplantation, amrinone was administered intravenously to 27 individuals with a transpulmonary gradient and pulmonary vascular resistance in the abnormal range. Twenty-four of 27 patients (89%) responded positively. Twenty-one of 27 (78%) went on to transplantation and 20 of 21 (95%) survived the procedure. A second study compared amrinone therapy with conventional therapy in 38 potential transplant candidates with pulmonary hypertension. Amrinone was more effective in reducing pulmonary hypertension than conventional therapy with high-dose diuretics, digitalis, and captopril (86% v 63%). Survival rate of those awaiting transplantation was also significantly higher in the amrinone group (91% v 63%). Although the protocol for comparing the two regimens does not allow for extrapolation of the results (amrinone was administered in-hospital under close monitoring, whereas conventional therapy was self-administered at home), the findings confirm the clinical impression that amrinone seems more effective and safer than conventional therapy in the treatment of potential heart transplant patients with pulmonary hypertension.