As part of a door-to-door survey, we screened for stroke among the inhabitants of three Sicilian municipalities (n = 24,496 as of November 1, 1987). Neurologists then investigated those subjects suspected to have had a stroke. Diagnoses of first-ever strokes were based on specified criteria and were reviewed by an adjudication panel. We found 189 subjects who had experienced at least one completed stroke (180 definite, 9 possible); 15 strokes were hemorrhagic, 71 ischemic, and 103 uncertain. The prevalence (cases/100,000) was 771.6 in the total population and 1,893.6 in those aged 40 years or over. The prevalence increased steeply with age, was higher in men between 60 and 79 years, but was higher in women thereafter. Age-specific figures were similar in the three study municipalities. Although all first-ever strokes had been previously diagnosed, 40% of the subjects had not been hospitalized for this condition.