A 57-year-old woman was admitted to our hospital for the treatment of mitral regurgitation and giant bulla with severe pulmonary hypertension. A dobutamine-induced test performed preoperatively resulted in a decrease of the systolic pulmonary artery pressure by 30 mmHg. Subsequently, mitral valve replacement and bullectomy were performed concomitantly. The patient recovered from heart failure, and the pulmonary artery pressure clearly decreased during the perioperative period. This case report serves to demonstrate the effectiveness of performing a one-staged operation for mitral regurgitation and giant bulla with severe pulmonary hypertension.