Background. The demand for transplantable organs exceeds donor supply. Patients with central nervous system (CNS) or other tumors are controversial donors, and the donor cancer transmission rates in cardiothoracic transplant recipients have not been determined. The Israel Penn International Transplant Tumor Registry (IPITTR) was queried to define the risk of donor cancer transmission in cardiothoracic transplant recipients. Methods. All heart, lung, or heart-lung recipients of organs from donors with a history of malignancy were reviewed. Donor and recipient demographics, histologic findings, and recurrence were reviewed. Results. Twenty-two patients received 17 hearts, 3 lungs, and 2 heart-lung transplants from donors with known CNS or other malignancies. No malignancy transmissions were noted with astrocytomas (n = 3) or glioblastomas (n = 1), except a medulloblastoma that recurred at 6 months, The transmission rate for CNS tumors was 17% (1 of 6), and 1- and 3-year survivals were 67% and 50%, respectively. The most common non-CNS donor cancer was renal cell carcinoma (n = 5), Two renal cell cancer transmissions occurred, both when vascular extension was present. The most aggressive tumor transmission was choriocarcinoma (n = 2) and melanoma (n = 2). Two of 3 choriocarcinomas metastasized with 67% mortality, and both melanomas were transmitted and resulted in death, Other donor cancers included angiosarcoma (n = 2), cervical (n = 1), lung (n = 1), prostate (n = 1), and a liver adenocarcinoma. The transmission rate for all non-CNS groups was 56 % (9 of 16) with a 2-year survival of 40%. Conclusions. The IPITTR experience indicates that tumor transmission is high (10 of 22, 45 %) in cardiothoracic transplant recipients. Similar to intra-abdominal organ recipients in the IPITTR, (1) renal cell carcinomas without capsular invasion appear safe with no transmission, (2) vascular invasion in renal cell carcinoma appears to result in early tumor transmission, and (3) melanoma and choriocarcinoma have high rates of transmission with early and almost universal death.