Background and purpose: The aim of this study was to demonstrate the different results obtained from a population-based and a hospital-based stroke study in the same city. Methods: Between January 1 and December 31, 1993, we collected information on all of the first strokes in the population of the city of Dijon, in conjunction with the Dijon Stroke Registry, collecting the first-ever strokes from patients living in Dijon as well as on all the first strokes in residents and nonresidents of Dijon who were treated at Dijon University Hospital. Demographic details, medical history, vascular risk factors, stroke subtype, as diagnosed by CT scan, and mortality rates were compared between the strokes observed in the population of the city of Dijon among residents as well as nonresidents in Dijon who were treated at Dijon University Hospital. Results: We collected information on 210 strokes observed in the population of Dijon city, 171 Dijon residents and 395 non-Dijon city residents hospitalized at the University Hospital of Dijon. These three groups were quite different. The residents of Dijon treated for stroke at the University Hospital were younger and their incidence of cerebral hemorrhage, cardiac arrhythmia, ischemic heart disease and case fatality rate were higher than those from the Dijon Stroke Registry. Conclusions: Type of stroke data bank is very important in order to describe cerebrovascular disease. Hospital-based studies tend to include more severe strokes, those occurring in a younger population, and those having a higher mortality. Population-based studies, on the other hand, give a somewhat different picture of stroke.