To estimate the severity of right ventricular hypertension noninvasively, the two-dimensional echocardiograms of 86 patients were examined--26 patients with atrial septal defect (ASD group), 22 with rheumatic valvular heart disease (VHD group), 12 with primary pulmonary hypertension (PPH group) and 26 with tetralogy of Fallot (Fallot group)--and data were compared with those of 20 normal persons. The interventricular septal (IVS) curvature index (delta r) from short axis view correlated well with the ratio of right to left ventricular systolic pressure (RVP/LVP). When IVS became convex towards the right ventricular cavity, the correlative coefficient between delta r and RVP/LVP was r = 0.75 in the ASD group, r = 0.83 in the VHD group, r = 0.71 in the PPH group and r = 0.77 in the Fallot group. The RVP/LVP approached a plateau when IVS became straight or convex towards the left ventricular cavity. Two-dimensional echocardiography provides a useful means to assess the right ventricular systolic pressure non-invasively.