BACKGROUND Residual regurgitation after transcatheter edge-to-edge mitral valve repair (TMVR) is a predictor of poor prognosis in patients with functional mitral regurgitation (FMR). This study sought to identify the mitral valve (MV) parameters measured by three-dimensional transesophageal echocardiography (3D-TEE) and MV leaflet features that predict residual mitral regurgitation (MR) after TMVR in patients with FMR. METHODS Consecutive patients with FMR who underwent TMVR were classified into two groups based on the degree of residual MR just after TMVR: < 2+ in the optimal MR reduction group and ≥ 2+ in the suboptimal MR reduction group. The two groups were compared with respect to 3D-TEE parameters and the MV leaflet features, including the following parameters: stiffness, defined as a leaflet that remains at a fixed angle even during diastole, and thickness, measured in both clear and rough zones. RESULTS Thirty-four of 46 patients (74%) were classified as the optimal MR reduction group. Multivariable analysis showed that anterior mitral leaflet + posterior mitral leaflet length/anteroposterior annulus diameter (p = .044) and MV leaflet stiffness (p = .007) were independent predictors of residual MR. CONCLUSIONS MV leaflet stiffness and the ratio of MV leaflet lengths to the annulus diameter may be good predictors of residual MR after TMVR in patients with FMR.