BackgroundStroke risk is higher in black ethnic groups compared with white. Although risk factors for stroke are known to differ between these populations, few population studies have reported on the risk of aetiological stroke subtypes in black ethnic populations.MethodsEthnic group differences in incidence of first ever ischaemic stroke by aetiological subtype were investigated with the South London Stroke Register (SLSR). The SLSR is a population based stroke register covering a multi-ethnic inner city population of 271 871 inhabitants comprising 63% white, 28% black and 9% other ethnic group. A modified pathophysiological Trial of ORG 10172 in Acute Stroke Treatment (TOAST) classification of stroke was used to estimate patterns of aetiological subtype and stroke was subtyped into large artery atherosclerosis (LAA), cardioembolism (CE), small vessel occlusion (SVO), other aetiology (OTH), undetermined …