The recent development of a new multigate pulsed Doppler system used in conjunction with an A-mode scan allows real time display of the velocity profiles across the vessel and quantitative flow measurement. Experimental in-vitro and in-vivo studies showed an excellent correlation between flow measurements obtained by this noninvasive method and by direct timed collection. Preliminary results of the post-occlusive hyperaemic response in normals and in patients with iliac stenosis are presented. Although no statistical comparison is allowed, it appears that the hyperaemic response is diminished when an iliac stenosis is present. A non-invasive method of quantifying the haemodynamic significance of profunda femoris artery stenosis is described. Finally, the velocity profiles and the flow curves in PTFE grafts were studied and compared to the flow patterns of the normal superficial femoral artery. The differences observed between the two conditions might explain the low patency rate of the synthetic grafts. Other fields of application of the method are suggested. The future development of a Duplex scanner combining B-mode imaging and the multigate Doppler system will allow the exploration of vessels within the abdomen and thorax: portal vein, in situ or transplanted renal arteries, ascending and abdominal aorta.