With the exception of carcinomas of the skin and lip, carcinoma of the bronchus is the most common carcinoma that afflicts recipients of solid organ grafts. Of 859 tumors occurring in 830 recipients of thoracic organs reported to the Cincinnati Tumor Transplant Registry, 242 were carcinomas and 68 of these were bronchogenic carcinomas, which therefore made up 8% of the overall total. There are, however, relatively few reports of heart transplant patients with bronchogenic carcinoma in the literature. We present details of four patients who developed this malignancy out of a total of 196 patients who survived and have been followed up for more than 3 months at our center, an incidence of 2%. The mean period from the time of transplant to diagnosis of malignancy was 58 months (range 11-82 months). The histology was squamous or anaplastic in three cases, and adenocarcinoma in one. Immunosuppressive therapy was reduced in all cases. Resection was carried out in two patients (both of whom died 6 and 11 months later, respectively), resection was combined with chemotherapy and radiation in one patient (alive 15 months later), and therapy consisting of radiation alone was given to one patient (died within 1 month). We conclude that bronchogenic carcinoma is relatively common in patients with heart transplants and that it has a poor prognosis.