A unilateral pulmonary artery agenesis, which develops occasionally as one of the associated anomalies in congenital cardiovascular defect like as tetralogy of Fallot, is very rare anomaly as an isolated congenital defect. The diagnostic approach for the pulmonary artery agenesis is first suggested by the unique appearance of the involved lung on a routinely checked chest roentgenogram, because most patients are asymptomatic unless pulmonary infection had been superimposed. We have recently experienced a case of left pulmonary artery agenesis, which was diagnosed by perfusion scan, digital subtraction angiogram and then treated by left pneumonectomy in a 9 year-old boy, and presented hereby with the review of relevant literature.