First-line investigations for all patients include full blood count, erythrocyte sedimentation rate, plasma glucose, plasma cholesterol, plasma electrolytes, creatinine. ECG, chest X-ray and colour Doppler sonography of the neck. Carotid selective arteriography is performed when colour Doppler of the symptomatic carotid artery shows a stenosis of about 70% or more, provided the patient is fit for carotid endarterectomy. The search for paroxysmal atrial fibrillation is worthwhile in patients with palpitations. Transesophageal echocardiography is indicated if a cardiac source of embolism is suspected on the basis of clinical examination, ECG or chest X-ray and in patients without any apparent cause of stroke, if an embolic mechanism is likely. Finally, in the young patient atherosclerosis is so rare that special etiological investigations are justified.