The following study was performed for the purpose of non-invasive and quantitative measurement of the blood flow volume in the deep-seated abdominal artery using an ultrasonic pulsed Doppler duplex system. The diameter of the human superior mesenteric artery was observed by M-mode. The diameter, flow velocity and flow volume in the canine superior mesenteric artery were measured, simultaneously using an electro-magnetic flowmeter and an ultrasonic pulsed Doppler duplex system. On the recording paper, those phasic changes were analysed. A time-average flow was acquired by multiplying the mean cross sectional area by the sum of the velocity integrals from the Doppler spectrum in one minute. The change in cross sectional area in the human superior mesenteric artery during one pulse was 13% of the minimum value. In the canine superior mesenteric artery, a close similarity among the phasic changes of the diameter, velocity and flow volume was shown. A close correlation was proven between the flow volume values by the electro-magnetic flowmeter and by the pulsed Doppler duplex system. The ratio between the values of the blood flow volume by the electro-magnetic flowmeter and that by the ultrasonic duplex system was 0.50 at the top of the systolic phase, 0.67 at the late diastolic phase, and 0.62 in the time-average. Applying this method to obtain the time-average flow volume using the ultrasonic duplex system, the blood flow volume of the superior mesenteric artery was measured percutaneously in 23 normal volunteers. The value was 505±189 ml/min (Mean±S.D.).