Pentacuspid pulmonary valve is an extremely rare congenital anomaly. A 71-year-old woman presented with dyspnea on exertion. The preoperative examination showed a large pulmonary artery aneurysm with severe pulmonary regurgitation. The pentacuspid pulmonary valve was an intraoperative finding with four equivalent leaflets and one hypoplastic leaflet. The valve was successfully repaired by use of a bicuspidization technique combined with annuloplasty, and pulmonary artery reduction was performed. Postoperatively, the patient remained asymptomatic with trivial pulmonary regurgitation 1 year later. To our knowledge, this is the first report of a pentacuspid pulmonary valve repair.