A 26-year-old woman was referred to our department due to cardiac tumor. She was asymptomatic, and transthoracic echocardiography showed accessory mitral valve tissue (AMVT) associated with cleft mitral valve. There was no left ventricular outflow obstruction, but we could identify the three-dimensional movement of AMVT and cleft mitral valve. Four-dimensional transthoracic echocardiography enabled us to reveal the real time movement of these structures precisely. In particular, en face visualization of cleft mitral valve and accessory mitral valve cannot be obtained by two-dimensional echocardiography. (Echocardiography 2013;30:E114-E115).