Conventional methods for determining mass of the left ventricle (LV) require geometric assumptions. Eleven patients were studied with ultrafast computed tomography (CT) and with two-dimensional echocardiography (2-D echo) for calculation of LV mass. With ultrafast CT, calculations were performed on end-systole images and end-diastole images for each patient. Comparisons of the results from ultrafast CT with those from 2-D echo were made with linear, Spearman rank, and interclass correlation coefficients, as well as with slope and intercept values of regression lines. Adequate ultrafast CT and 2-D echo studies were obtained in nine of the 11 patients. After the systolic and diastolic ultrafast CT determinations of LV mass were averaged, the results demonstrated excellent agreement with the 2-D echo determinations (slope = 1.0 +/- 0.20, r = .89, P less than .002).