This study included 40 patients over 60 years of age with echocardiographic findings of mitral valve prolapse (MVP). Most of these patients were unaware of any cardiac disorder until the time of echocardiography. In the majority, the clinical manifestations were benign, and the duration of symptoms variable. Congestive heart failure (CHF) was noted in 10 patients (25 percent) who were unaware of having any cardiac disorders until the onset of their symptoms. In 5 patients (4 with CHF and 1 with endocarditis), surgical replacement of the prolapsed mitral valve was necessary. Endocarditis was present in 4 patients (10 percent), none of whom had been instructed in the prophylactic use of antibiotics. The physician's awareness of mitral valve prolapse in the elderly patient is important, since the disorder may not be as benign in aged patients as in younger ones, and life-threatening complications may occur.