In a 65-year-old woman with vertebrobasilar transient ischaemic attacks (TIAs) and subclavian steal, a steal phenomenon in the basilar artery could be demonstrated by transcranial Doppler sonography after provocation with postischaemic hyperaemia of the arm on the affected side. It was not possible to provoke symptoms or signs at the time. The significance of finding a steal phenomenon in the basilar artery even in a patient with a history of vertebrobasilar TIAs is discussed.