One hundred twenty-two cases of the adult form of the scimitar syndrome were collected from different cardiologic centers. The clinical, radiographic and hemodynamic findings are described. The scimitar syndrome is defined as an anomalous right pulmonary venous drainage, partial or complete, to the inferior vena cava. Additional characteristics of this syndrome such as hypoplasia and abnormalities of the vascular supply to the right lung, dextrocardia and abnormalities of the bronchial segmentation are common; bronchiectases are rare. The left to right shunt was less than 50% in 100 of the 122 patients. The pulmonary arterial pressures were normal in 94 patients and slightly elevated in 28. A follow-up study of these patients showed that, without surgical correction, they lead a normal life. An awareness of this syndrome may avoid unnecessary invasive diagnostic procedures and surgical treatment for most patients.