Background and objective Pre-operative assessment of mitral valve (MV) anatomy is essential to surgical design in patients undergoing MV repair. Although 2-dimensional (2D) echocardiography provides precise information regarding MV anatomy, RT-3D TEE could increase the understanding of MV apparatus and individual scallop identification. We aimed to investigate the value of RT-3DTEE in MV repair. Methods RT-3DTEE was performed in six patients with mitral valve prolapse (MVP) by using Philips IE33 with X7-2t probe. Preoperative RT-3DTEE studies were compared with surgical findings in patients undergoing surgical mitral valve repair, and quantitative evaluation was performed by QLab 6.0 software before and after surgical mitral valve repair. Results RT-3DTEE could display dynamic morphology of MV, the location of prolapse, and spatial relation to the surrounding tissue. It could provide surgical views of the valves and the valvular apparatus. These results were consistent with surgical findings. The quantitative evaluation before and after surgical MV repair indicated that anterolateral to posteromedial diameter of annulus, anterior to posterior diameter of annulus, perimeter of annulus, and area of annulus in projection plane were significantly smaller after operation compared with those before operation (P<0.05). The length of posterior leaflet, the area of anterior and posterior leaflet, the maximal prolapse height, the volume of leaflet prolapse and the length of coaptation in projection plane were significantly reduced after operation (P<0.05). Conclusion RT-3DTEE is a unique new modality for rapid and accurate evaluation of mitral valve prolapse and mitral valve repair.