Scimitar syndrome (also known as hypogenetic lung syndrome or congenital venolobar syndrome) is a type of partial anomalous pulmonary venous return in which one of the right pulmonary veins is draining into the systemic circulation (instead of draining into the left atrium). Most commonly it drains into the inferior vena cava (less commonly it drains into the suprahepatic veins, the superior vena cava or the right atrium) making it take the shape of a Turkish sword (thus the name Scimitar syndrome), most of the time the right lung is also abnormal (small sized).

Scimitar syndrome can be asymtomatic or can be associated with symptoms related to pulmonary hypertension or pulmonary malformation, most commonly it causes recurrent infections of the right lung, hemoptysis and pulmonary hypertension.

On chest X-ray, Scimitar syndrome is easily diagnosed by demonstrating the abnormal shape of the scimitar vein in the right lower lung zone and small size of the right lung, on CT scan, the various anatomical malformation of the lung, the heart, the pleura and the pulmonary veins are demonstrated easily.