We describe a 66-year-old man who required an operation for severe mitral regurgitation associated with a double-orifice mitral valve. Real-time 3-dimensional transesophageal echocardiography clearly demonstrated a double-orifice mitral valve with a central fibrous bridge. A flail posterior leaflet was observed on the anterolateral mitral valve orifice. Mitral valve repair using P1 triangular resection, anterolateral commissure plication, and ring annuloplasty with Duran band (Medtronic, Minneapolis, MN) was successfully performed. Postoperative real-time 3-dimensional transesophageal echocardiography demonstrated a double-orifice mitral valve without regurgitation or stenosis.