For visualizing blood flow in the human heart noninvasively, the stream-function method based on the ultrasonic Doppler technique was introduced. In this method intracardiac blood flow is displayed as a two-dimensional streamline distribution pattern. In normal hearts, blood flow in the left ventricle during systole is displayed as a fan-shaped streamline pattern converging from the whole ventricular wall toward the outflow tract, and in diastole the streamline distribution shows fan-shaped divergence from the left atrium toward the whole ventricular wall. The fan-shaped streamline distribution is considered to reflect the uniform contractability and extensibility in the whole ventricular wall. On the other hand, in infarcted hearts with regional asynergy in the left ventricle, the streamline pattern is remarkably different. In systole, the streamline pattern at the normokinetic portion is the same as that in normals, but in the infarcted portion, the streamlines show a crooked pattern caused by the inflow into and the outflow from the ventricular aneurysm. In diastole, streamlines toward the infarcted portion disappeared. Changes in streamline patterns in both cardiac phases show the regional asynergy in the infarcted heart. From these results, it can be said that the intracardiac blood flows are visualized by the stream-function method, and this method is considered to be very useful for analyzing the intracardiac blood flow.