Ischaemic stroke is a major cause of death in industrialised nations. Many survivors of stroke bear a burden of permanent disability. This very often involves extreme individual suffering and puts great financial strain on healthcare systems.It is beyond doubt that ischaemic stroke can partly be avoided. In order to reduce the incidence of stroke, 2 approaches to prevention are necessary. First, avoidable risk factors must be avoided by patients themselves. Secondly, treatable risk factors must be treated by physicians. However, efficient preventive strategies depend on the reliable definition and recognition of risk factors and their competent management.In the last few decades, scientific research has identified certain disorders and conditions as definite risk factors and has meticulously assessed their significance for the causation of stroke. The significance of various other potential risk factors, however, remains elusive. The most important treatable risk factors for ischaemic stroke are cardiac disease, arterial hypertension, diabetes mellitus, hyperlipidaemia, increased fibrinogen level, elevated haematocrit, and selected haematological disorders and coagulopathies. The most important avoidable risk factors include cigarette smoking, alcohol consumption, abuse of other drugs, intake of oral contraceptives, excessive bodyweight and low physical activity. Implications for the prevention of ischaemic stroke, in particular with respect to underlying cardiac disease, are outlined.