We report a case of a 4-year-old boy with tetralogy of Fallot, pulmonary atresia, and hypoplastic pulmonary arteries who presented with mild hemoptysis and upper respiratory infection 3 weeks following percutaneous transluminal angioplasty for pulmonary artery stenosis. While pneumonia was initially suggested on early plain radiographs of the chest, a large pseudoaneurysm of a right lower lobe pulmonary artery branch was subsequently diagnosed with CT and angiography.