The optimal plane for measurement of the right ventricular (RV) volumes by real-time three-dimensional echocardiography (RT3DE) was determined and the feasibility and accuracy of RT3DE in studying RV systolic function was assessed. RV "Full volume" images were acquired by RT3DE in 22 healthy subjects. RV end-diastolic volumes (RVEDV) and end-systolic volumes (RVESV) were outlined using apical biplane, 4-plane, 8-plane, 16-plane offline separately. RVSV and RVEF were calculated. Meanwhile tricuspid annual systolic excursion (TASE) was measured by M-mode echo. LVSV was outlined by 2-D echo according to the biplane Simpsons rule. The results showed: (1) There was a good correlation between RVSV measured from series planes and LVSV from 2-D echo (r=0.73; r=0.69; r=0.63; r=0.66, P＜0.25-0. 0025); (2) There were significant differences between RVEDV in biplane and those in 4-, 8-, 16-plane (P＜0. 001). There was also difference between RV volume in 4-plane and that in 8-plane (P＜0.05), but there was no significant difference between RV volume in 8-plane and that in 16-plane (P＞0.05); (3) Inter-observers and intro-observers variability analysis showed that there were close agreements and relations for RV volumes (r=0. 986, P＜0. 001; r=0.93, P＜0. 001); (4) There was a significantly positive correlation of TASE to RVSV and RVEF from RT3DE (r=0.83; r=0.90). So RV volume measures with RT3DE are rapid, accurate and reproducible. In view of RVs complex shape,apical 8-plane method is better in clinical use. It may allow early detection of RV systolic function.