A 67 year-old female patient was admitted to our hospital with the complaints of dyspnea, cough, expectoration, hemoptysis and chest pain. Her CT examination revealed left upper atelectasis but could not demonstrate left pulmonary artery. Perfusion scan showed extremely reduced perfusion on the left. In concert with these, MR angiography demonstrated proximal interruption of left pulmonary artery and very thin immediate branches.These findings led to the diagnosis of left pulmonary artery hypoplasia with upper lobe atelectasis. This pathology is presented here for its extreme rarity.