Unilateral pulmonary artery agenesis is a rare congenital anomaly usually associated with other cardiovascular anomalies such as tetralogy of Fallot or septal defect. Unilateral pulmonary artery agenesis without other coexisting cardiovascular abnormality (isolated unilateral pulmonary artery) is extremely rare and often asymptomatic until adulthood. In these patients, diagnostic clue is found in a plain chest roentgenogram, showing a hyperlucent contracted hemithorax. We have recently experienced a case of isolated right pulmonary artery agenesis, which was diagnosed by chest dynamic CT, perfusion scan, echocardiogram and 3-dimensional reconstruction cardiac CT angiography in a 50-year old female who had suffered from mild dyspnea on exertion and improved with conservative treatment. We report this case with a brief review of the relevant literature.