Infection of the mitral-aortic intervalvular fibrosa occurs most commonly in association with infective endocarditis of the aortic valve. Infection of the aortic valve results in a regurgitant jet that presumably strikes this subaortic interannular zone of fibrous tissue and produces a secondary site of infection. Infection of this interannular zone then leads to the formation of subaortic abscess or pseudoaneurysm of the left ventricular outflow tract. This infected zone of mitral-aortic intervalvular fibrosa or subaortic aneurysm can subsequently rupture into the left atrium with systolic ejection of blood from the left ventricular outflow tract to the left atrium. This report describes the echocardiographic findings in three patients with pathologically proved left ventricular outflow tract to left atrial communication. Precise preoperative diagnosis is important, and this lesion should be differentiated from ruptured aneurysm of the sinus of Valsalva and perforation of the anterior mitral leaflet. Transthoracic echocardiography using color flow imaging and conventional Doppler techniques may show an eccentric mitral regurgitation type of signal in the left atrium originating from the region of the left ventricular outflow tract. However, transesophageal echocardiography provides an accurate preoperative diagnosis and should be used intraoperatively during repair of such lesions.