The present study was designed to determine whether the long axis of the left ventricle is elongated in patients with aortic regurgitation. Among 445 patients with valvular disease who were followed in our hospital from April 1986 to February 1987, 14 with aortic regurgitation [AR: age: 46.1 (mean) +/- 17.6 (standard deviation) years] and 17 with mitral regurgitation (MR: age: 48.8 +/- 18.0 years) were selected for analysis. They all had optimal quality images in the apical view of the two-dimensional echocardiograms adequate for the evaluation and moderate to severe regurgitation at the time of Doppler examination. The control group consisted of 15 subjects without evidence of organic heart disease (age: 44.9 +/- 17.7 years). There was no difference in the mean duration of the clinical course between AR (14.9 years) and MR (13.4 years). The following measurements were made in the apical right anterior oblique view: Lo (long-axis distance of the outflow tract); from the left ventricular apex to the center of the aortic annulus, L (long-axis distance of the left ventricle); from the apex to the junctional point between the aortic and mitral valves, Li (long-axis distance of the inflow tract); from the apex to the center of the mitral valve ring, and d1, d2 and d3 (apical, middle and basal short axes of the left ventricle); the distances perpendicular to the each long axis at the levels of 1/4, 2/4 and 3/4 of the long axis. All data were corrected by means of the calibration scale, and compared as indices divided by the body surface area.(ABSTRACT TRUNCATED AT 250 WORDS)