The use of both Doppler and pulse-echo ultrasonic equipment for detecting carotid artery disease is discussed. The need for new non-invasive techniques, capable of detecting small stenoses, is demonstrated and the development of two techniques (analysis of blood velocity waveforms and the measurement of arterial wall movement) is described. The arterial wall movement showed no change with disease, but analysis of the blood velocity waveforms proved capable of detecting even minor stenosis in some cases. Methods for confirming these preliminary results are discussed.