The unilateral absence of a proximal pulmonary artery (UAPPA) is rare and is most frequently accompanied by cardiovascular anomalies such as tetralogy of Fallot or septal defects. We report a patient with truncus arteriosus with UAPPA in which we performed a two-stage surgical repair. During the first palliative operation, a right modified Blalock-Taussig shunt was constructed to develop the hypoplastic right pulmonary artery. At 10 months, the patient underwent patch closure of a ventricular septal defect with integration of both pulmonary arteries, and reconstruction of the right ventricular outflow tract using a conduit. Four years postoperatively, he continues to do well.