Background: The remodeling of right ventricle (RV) determining tricuspid valve (TV) geometry and the severity of functional tricuspid regurgitation (TR) has not been clearly demonstrated. Methods: In 40 patients with various degrees of functional TR and in sinus rhythm, RV and TV geometries were analyzed using real-time 3-dimensional echocardiography, including tenting angles of anterior (A慣), posterior (P慣) and septal (S慣) leaflets, septal-lateral and antero-posterior tricuspid annulus diameters, inlet septal-lateral and antero-posterior RV dimensions in 1 cm apart from annulus planes, mid-RV septal-lateral dimension, and the distance between annulus and apex. A mid-systole frame when the TV tenting is smallest was selected for the analysis. Results: By multiple stepwise linear regression analyses, A慣(r=0.64, p<0.001) and S慣(r=0.69, p<0.001) were mainly determined by mid-RV septal-lateral dimension, while P慣 (r=0.45, p<0.005) was by the distance between annulus and apex. Septal-lateral (r=0.74, p<0.001) and antero-posterior annulus diameters (r=0.71, p<0.001) were mainly determined by inlet septal-lateral and antero-posterior RV dimensions, respectively. TR distal jet area correlated significantly with A慣 (r=0.65, p<0.001), P慣 (r=0.48, p<0.005), S慣 (r=0.64, p<0.001), septal-lateral (r=0.72, p<0.001) and antero-posterior (r=0.43, p<0.01) tricuspid annulus diameters, inlet septal-lateral (r=0.61, p<0.001) and antero-posterior (r=0.38, p<0.05) RV dimensions, mid-RV septal-lateral dimension (r=0.60, p<0.001), and the distance between annulus and apex (r=0.51, p<0.005). TR vena contracta width showed similar results. TR distal jet area was mainly determined by septal-lateral annulus diameter and A慣 by multiple stepwise linear regression analysis. TR vena contracta width was determined by septal-lateral annulus diameter, inlet septal-lateral RV dimension and A慣. Conclusions: TV leaflet tenting is determined by mid-RV septal-lateral dilation and annulus-apex elongation. Tricuspid annulus dilation is closely linked with inlet RV dilation. Functional TR severity seems to be determined by septal-lateral annulus and RV dilation rather than antero-posterior dilation.