Combined heart and lung transplantation was carried out in 17 patients at Stanford University between March, 1981, and December, 1983. The recipients were between 22 and 45 years old. All patients had end-stage pulmonary hypertension; 10 had Eisenmenger's syndrome and the remaining 7, primary pulmonary hypertension. Five patients died within the first few postoperative weeks. The remainder are well between four weeks and 33 months from operation. The immunosuppressive protocol has consisted of cyclosporine with an initial course of rabbit antithymocyte globulin. Azathioprine also was given for the first two weeks and then was replaced with prednisone. Rejection, as diagnosed by cardiac biopsy, was treated with high doses of methylprednisolone. Modifications of technique that have developed include the removal of the recipient heart and lungs separately, and preservation of the lungs with a modified Collins' solution instead of a cardioplegic solution. Rejection occurred in 6 of the 12 survivors. Infections developed in 9 patients, but only one resulted in a fatal outcome (Legionella). Thus, the results of clinical heart-lung transplantation have been considerably superior to clinical efforts in lung transplantation. It is suggested that the combined operation is preferable for the following reasons: (1) all diseased tissue is removed, thus eliminating recurrent infection and ventilation/perfusion disparity; (2) transplantation of the entire heart-lung block preserves coronary-bronchial vascular anastomoses and makes airway dehiscence less likely; and (3) to date, diagnosis of rejection by cardiac biopsy has appeared to be a satisfactory method of diagnosing and treating pulmonary rejection.(ABSTRACT TRUNCATED AT 250 WORDS)