The Unilateral Absence of a Pulmonary Artery(UAPA) is an uncommon but not rare congenital anomaly. This defect was first recognized by Fr ntzel in 1868, and first confirmed by angiocardiography by Madoff et al. in 1952. The UAPA is frequently associated with other anomalies of the heart and the great vessels, such as patent ductus arteriosus in about one third of cases with right sided lesion and tetralogy of Fallot in 40% of cases with left sided lesion. But it may occur as an isolated lesion which is the case of this report. Adults with isolated UAPA may be asymptomatic so the diagnosis may the case of this report. Adults with isolated UAPA may be asymptomatic so the diagnosis may be delayed. But unless this entity is recognized in early stage, a potentially curable lesion may become inoperable because of the development of pulmonary hypertension. The diagnosis may be commonly suspected from the chest roentgenogram and confirmed by angiocardiography. Aortography is essential for the recognition of the collateral arterial supply to the anomalous lung. We experienced a case of an asymptomatic 24-year-old male whose routine chest roentgenogram suggested the possibility of absence of right pulmonary artery. His chest film revealed marked reduction in right lung volume associated with shifting of the heart and mediastinum to the right side and elevation of the right hemidiaphragm. Difference in the vascularity of the two lung fields was evident and the hilar comma shadow could not be identified on the right ventriculography. Aortography revealed multiple coarse lace-like vascular structures supplying the right lung from the dilated bronchial arteries. This is the first case report of an isolated absence of right pulmonary artery in Korea, so we present the case with a brief review of literature with the emphasis on its roentgenographic manifestations.