In the past year the search for genetic susceptibility factors involved in ischaemic stroke has motivated a number of important studies in humans and animals. These have been focused on genetic susceptibility as a risk factor for ischaemic stroke, or as a determinant of ischaemic stroke outcome. Because there is increasing evidence that genetic factors play a role, it seems that epidemiological studies assessing both environmental and genetic risk factors may help to understand the cause of ischaemic stroke better. This may have therapeutic and preventive implications. Curr Opin Neurol 12:47-55. (C) 1999 Lippincott Williams & Wilkins.