Ultrasound has provided a highlight of the different types of subclavian steal. The authors report epidemiological and clinical data concerning 40,000 ultrasound examinations performed on epiaortic arteries and particularly the last 12,000 in which Doppler c.w., duplex scanner and transcranial Doppler were used. Various types of steal are described; five types of subclavian steal have been classified and patients stratified as being symptomatic and asymptomatic. The neurological symptoms are divided as follows: generalized cerebral ischemia, vertebro-basilar ischemia and hemispheric ischemia. Based on this clinical and haemodynamic outline, surgical therapy is indicated and type of surgery suggested.