This paper deals with a system for computer-aided analysis of M-mode and two-dimensional sector scan echocardiograms. Echo data obtained using conventional ultrasound instruments are recorded on video tape through special interface circuits without a video camera, and the echo data on video tape, which can be displayed on an oscilloscope of the instrument repeatedly with the same quality as the original data, are transferred to a minicomputer through the interface circuits. The M-mode echocardiogram for about 1. 6 seconds is usually digitized into 256 multiplied by 200 pixels with 8-bit gray levels and then processed automatically by the minicomputer. After detecting the positions of cardiac structures, i. e. , interventricular septum and posterior wall endocardium and epicardium of left ventricle, cardiac information, such as changes of wall thickness, diameter, volume and velocity of circumferential fiber shortening of left ventricle, is obtained. Automated analysis of the two-dimensional sector scan echocardiogram is under development and only simple results are shown.