Thalassemia patients succumb at a young age to congestive heart failure. Hitherto, attention has been focused on left ventricular function. This report emphasizes right ventricular dysfunction and abnormal pulmonary function. We performed cardiopulmonary evaluation, including echo-Doppler, spirometry, CO diffusion (DCO), and blood gas analyses in 35 patients with homozygous beta-thalassemia maintained by multiple blood transfusions. Six autopsy lung specimens were studied. Thalassemia patients exhibited pulmonary dysfunction, characterized by hypoxemia (85 percent of the patients were outside the 95 percent confidence limits), reduced lung volumes (51 percent), flow rates (63 percent) and DCO (50 percent). Right ventricular dysfunction was more prevalent than left ventricular dysfunction. Furthermore, 75 percent of the patients had evidence of pulmonary hypertension consistent with more frequent right ventricular rather than left ventricular dysfunction. Our findings suggest that in thalassemia patients, complex cardiopulmonary abnormalities precede the final outcome of congestive heart failure.