A high-speed digital subtraction echography (DSE) technique was developed. The principle is serial image subtraction of successive frames of high-speed B-mode echograms. This system improves the time resolution and spatial resolution against a moving structure. Using this high-speed DSE, it was possible to demonstrate the electrically stimulated focus of experimental ventricular premature contraction caused by an artificial pacemaker in mongrel dogs. Local elasticity in the vascular wall of common carotid artery was assessed as the extent of systolic radial extension of an artery. With an ultrasonic contrast agent, the vector and stream lines of a cardiac cavity were also elucidated. It is concluded that high-speed DSE has great potential for detecting arrhythmia and early lesions of arteriosclerosis and in blood flow measurement without Doppler echography.<<ETX>>