Real-time, phased-array, two-dimensional echocardiographic studies identified ruptured chordae tendineae in five patients: four patients had a flail mitral valve and one had flail mitral and tricuspid valves. The characteristic abnormality was a rapid systolic motion of the involved leaflet beyond the line of valve closure into the atrium. The maximal abnormal systolic motion was greatest at the tip of the leaflet with a loss of the normal coaptation point. By contrast, the two-dimensional echocardiographic feature of mitral valve prolapse is an abnormal systolic motion that is maximal in the body of the leaflet with intact leaflet coaptation. Thus, two-dimensional echocardiography can identify flail mitral and tricuspid valves and is useful in distinguishing ruptured chorade from valvular prolapse.