The first aim of the study, to see every case of stroke and TIA which has occurred in a representative population, unbiased by hospital admission and with high pathological documentation, is being achieved. To date, the incidence rates for stroke in Perth are strikingly similar to those in other major population-based studies in the Western world. Further data on risk factors are likely to contribute greatly to our understanding of the aetiology of stroke. The data on stroke outcome should be of international significance.