The clinical usefulness of biplane color Doppler transesophageal echocardiography is illustrated by the results obtained in 300 successive examinations. The additional contribution of the newer longitudinal plane was judged significant or major in 64% of the cases. The method was useful mainly for intraoperative examinations, assessment of native valvular disease, prosthetic valve evaluation, search for tumors, and assessment of endocarditis, congenital heart disease, and aortic disease. In contrast, the longitudinal plane option was not contributory in 68% of the cases of thromboembolism. Typically, the technique aided in the evaluation of mitral valve insufficiency and the detection of paraprosthetic leaks. Lesions located at the level of the ascending aorta, the left and right ventricular outflow tracts, and the interatrial septum were also visualized best. The limitations of the method were negligible and the duration of the examination was not significantly increased in comparison to the monoplane method. When available, biplane transesophageal echocardiography seems to be preferred in most clinical settings.