A new technique, ultrasonic Doppler angiography, was used to examine the deep veins in 50 legs of 40 patients in which deep vein thrombosis was suspected. The results were compared with those of venography. The ultrasound method detected 30 out of 32 venographically confirmed thrombi and showed 17 out of 18 venographically proved normal deep veins. It was equally effective in detecting partial as well as totally occluding thrombi.