Abstract
A 48-year-old male with mitral prolapse syndrome underwent severe left heart failure due to rupture of chordae tendineae. The site of rupture was the strut chorda of the anterior leaflet, one third which was prolapsed. We performed mitral valve replacement, and met with good results in this case. Mitral prolapse syndrome caused by myxoid degeneration is progressive, so we must follow up intensively and timely surgical treatment should be performed.