Although several reports have showed the application of 3-dimensional (3D) echocardiography, it is hard to find a report regarding the intraoperative use of real time 3D transesophageal echocardiography (TEE) in mitral valve repair surgery. In the present case, real time 3D TEE the one from the one TEE probe position as well as their rotated and cropped images showed detailed spatial images enough for immediate assessment of the mitral valve deformity and the characteristics of mitral regurgitation flow. Under cardiopulmonary bypass (CPB) employing moderate hypothermia, the prolapsed mital leaflet was excised, the ruptured cord was repaired and an annuloplasty ring was inserted to reinforce the mitral valve and to close up the defect. The 2D and 3D TEE images after CPB showed effective repair providing complete closure of the mitral leaflets and absence of residual regurgitation flow. Considering that the conventional 2D TEE requires examiner's ability to gather the various 2D TEE images and experience essential for intergrating the 2D images for full understanding of spatial structure of valvular deformity and dysfunction, 3D TEE's ability for making a comprehensive spatial image from a limited number of 2D images seems to have an additional clinical efficacy in intraoperative TEE monitoring for cardiac value surgery.