Abstract: A method of measuring blood flow through tissue in a region of interest including the steps: injecting an ultrasonic tracer into the blood upstream of the region of interest and also upstream of a specified reference region; utilizing the tracer-produced echo intensity function to compute: (i) the mean transit time of the tracer through the region of interest; and (ii) the blood volume within the region of interest; and dividing the results of computation (ii) by computation (i) to produce a quantitative measurement of the blood flow through the tissue in the region of interest.