Double-orifice mitral valve is a relatively rare congenital abnormality, usually discovered at autopsy or surgery. In most cases, the double-orifice mitral valve causes no hemodynamic effects, sometimes it is regurgitant, and rarely is stenotic. Appreciation of this echocardiographic abnormality is important because double orifice mitral valve is often associated with other congenital anomalies and this echocardiographic findings may be confused with other cardiac abnormalities. The authors report a case of isolated congenital double-orifice mitral valve in a 42-year-old woman. Data from the literature are reviewed and the echocardiographic images of the malformation are described.