Pulmonary artery compression in adults resulting from tumors is an uncommon condition often associated with poor prognosis. Among the imaging modalities used for diagnosis, the role of trans thoracic echocardiography in identifying secondary pulmonic stenosis due to extrinsic or intrinsic compression and more importantly the physiologic significance has been increasingly recognized. We describe here a case of isolated left pulmonary artery stenosis which was initially suspected based on classic echocardiographic features of obstruction of pulmonary artery and subsequently confirmed by CT imaging. This case illustrates the versatility of trans thoracic echocardiography in diagnosing incidental abnormalities with potential significant consequences.