Patients with atherosclerotic carotid artery stenosis commonly have arterial disease elsewhere, especially coronary artery disease. The aim of the medical treatment is to reduce the incidence of stroke, myocardial infarction and vascular death. Both primary and secondary prevention of these vascular events requires control of vascular risk factors, particularly lowering elevated blood pressure, lowering of elevated blood cholesterol and stopping smoking. Aspirin and ticlopidine are effective in reducing vascular events in patients with atherosclerosis, with a relative reduction of about 25% for the composite outcome event "stroke, myocardial infarction or vascular death". Whether low dose (less than 100 mg/d), medium (300 mg/d) or high dose (1,000 mg/d or more) of aspirin confer the same degree of protection against vascular events is unclear. The gastrointestinal side effects are greater for the high dose than for the medium dose, but the difference between the medium dose and the low dose is very small. Ticlopidine conveys a modest risk of reversible severe neutropenia and is often used as a second-line drug, but this is a controversial issue. Heparin is often used as a short-term preventive treatment in patients with transient ischaemic attacks or minor stroke, especially in those with "crescendo" transient ischaemic attacks, progressing stroke, severe carotid stenosis or intraluminal thrombus.