Summary: Acute mitral insufficiency, originated from rupture of initral chordae tendineae secondary to nonpenetrating thoracic trauma, is an unusual condition. This diagnosis is difficult to establish because physical examination, electrocardiogram, and cardiac enzymes are neither sensitive nor specific. The diagnosis of rupture must be quickly established because this disorder may be fatal. This paper reports the c;ise ofa patient with acute initral insufficiency secondary to a mitral valve chord rupture a week after a nonpenetrating thoracic trauma.