Among 578 cases of Tetralogy of Fallot, 19 with absence left pulmonary artery were studied. When a patient has early and serious cyanosis and the stenosis of the outflow tract of right ventricle and/or the pulmonary artery is mild under echocardiographic examination, and at the same time, hemoglobin is markedly increased and SaO is rather low, the diagnosis of Tetralogy of Fallot with unilateral absence of pulmonary artery should be considered. The value of chest X-ray film is limited in this case. The diagnosis can be confirmed by selected angiography in the right ventricle which may reveal the anatomical deformity by the curved shadow or the drum-stick extremity in the left pulmonary artery.