Considering a worldwide average 1-year survival rate of nearly 90% after orthotopic heart transplantation, the question arises as to whether there is still an indication for heterotopic heart transplantation. Since 1967, 132 heart transplantations have been performed at our institution. From 1974 to 1983 only heterotopic transplantations were performed. Since 1985, quadruple-drug therapy has been used for immunosuppression. This consists of low dose cyclosporine in combination with azathioprine, methylprednisolone (in lower dosages), and rabbit antithymocyte globulin (for the first 4 to 6 days after operation and as rescue therapy for severe rejections). Fifty-five transplantations have been performed with this therapy (44 orthotopic and 11 heterotopic). The indications for heterotopic transplantations were either elevated pulmonary vascular resistance (4 to 6 Wood units, n = 6), or a gross donor and recipient weight mismatch (more than 20%) in candidates who showed signs of severe cardiac decompensation (n = 6). One patient had both indications. The 1-year survival rate for those patients was 83%. Currently seven of the 11 patients are alive with life spans ranging from 6 months to 2.5 years after operation. Causes of deaths were infections (n = 3) and chronic graft rejection (n = 1). The recipients were restudied with right-sided heart catheterizations performed from 2 months to 2 years after transplantation. In all patients the cardiac output increased significantly from a mean of 4.0 to 5.8 L/min (p less than 0.0005). In patients with elevated pulmonary vascular resistance, this value decreased after heterotopic transplantation from a mean of 4.9 to 2.4 Wood units.(ABSTRACT TRUNCATED AT 250 WORDS)