BACKGROUND Unilateral absence of a pulmonary artery (UAPA) is a rare congenital cardiovascular malformation. More than half of UAPA cases have other cardiac lesions such as tetralogy of Fallot or septal defects. Clinical manifestations are diverse and range from heart failure after birth to an incidental finding on chest imaging during adulthood. Whereas early surgical revascularization is recommended in infancy, this is usually not feasible in the adult population. Management in these patients is aimed at treating the complications of UAPA. CASE REPORT A 67-year-old woman was evaluated for subacute right heart failure. An echocardiogram revealed pulmonary stenosis, tricuspid regurgitation, and depressed right ventricular function. Chest computed tomography (CT) showed absence of the right pulmonary artery. Additionally, there was a lung tumor in the right upper lobe. Right-heart catheterization confirmed a critically obstructed pulmonary orifice shown by hemodynamic collapse when crossing the pulmonary valve with the catheter. The patient underwent pulmonary valve balloon dilatation with right ventricular outflow tract stenting followed by percutaneous implantation of a balloon-expandable stent-valve. The clinical course was complicated by a complete heart block. Oncologic management consisted of stereotactic radiotherapy. CONCLUSIONS The combination of UAPA, pulmonary stenosis, and lung cancer is rare. Pulmonary stenosis worsens prognosis in adult patients with UAPA, but also constitutes a therapeutic target. The decision to treat the pulmonary stenosis should be based on the severity of stenosis, the degree of pulmonary hypertension, and individual anatomy. We chose percutaneous pulmonary valve implantation because our patient had a critical pulmonary stenosis with normal pulmonary pressures.