Introduction: Recent studies revealed that stretch force cause by left ventricular (LV) remodeling stimulates mitral leaflet adaptation, and mitral leaflet area (MLA) and annuls area were increased in patients with hypertrophic cardiomyopathy. However, the effects of LV hypertrophy (LVH) caused by chronic pressure overloading on MLA itself and other mitral valve apparatus have not been elucidated. Methods: Real-time 3-dimensional echocardiography was done in 25 patients with LVH (aortic stenosis (n=10), hypertension (n=15) and 20 normal controls. A customized software (Omni4D) was used to obtain a validated measure of mitral leaflet surface area (MLA), mitral annular area and nonplanarity. LV mass was determined 3-dimensionally, and LVH was designated as ASE guideline described. All data were indexed to body surface area. Results: LV mass index was significantly higher in patients group compared to control (120.2짹23.1 vs. 70.5짹12.4 g/m², p<0.001). Indexed MLA was significantly larger in LVH group than normal (8.34짹1.84 vs. 6.6짹0.80 cm²/m², p<0.001). LVH group was also characterized by higher annulus area (AA) and annulus height (AH) (3.73짹1.38 vs. 3.06짹0.55 cm/m², P=0.02). In overall group, MLA index was well correlated with LV mass index (R=0.73, p<0.001). Indexed AA (R=0.58, p<0.001) and AH(R=0.48, p=0.01) had modest correlations with LV mass. Conclusion: Concomitant increase of MLA parallel to LVH is characteristic in LV pressure overloading, which suggests existence of a common mechanism.