In order to get a better epidemiological base for preventive intervention in the county of Ostergötland, Sweden, a comprehensive study of sickness absence was done. During the years 1985, 1986 and 1987, all new periods of sick-leave exceeding seven days were registered with demographic variables. This information was related to data about the total population of Ostergötland. Each year approx. 45,000 persons had approx. 61,000 sickness spells. These figures were stable over the years while the number of sick-leave days increased. Blue-collar occupations had the highest sick-leave rates and the female sick-leave rate was higher in general and much higher in most male-dominated occupations. The male rate was lower within female-dominated areas, except among secretaries and textile workers. Females in extremely male-dominated groups had the highest rates, while both male and female sick-leave rates were lower in more gender-integrated occupations.