The epidemiological pattern of genital herpes infections was studied by evaluating virus isolations and serological results based on samples collected from Göteborg and Malmö, the two largest urban areas of southern Sweden. 1087 strains of herpes simplex virus isolated from cases of clinical herpes in Göteborg during the period 1980 to 1987 were evaluated for type relatedness. It was found that type 1 constituted 10% of the overall number of strains isolated with insignificant variation from year to year and type 1 and 2 occurred in same proportions in men and women. The HSV type 2 specific seroprevalence in 1158 pregnant women from Malmö during the years 1973, 1979, 1987 and 1989 was studied. A significant increase in prevalence figures was noted from 1973 to 1987. The age-related seroprevalence of 1211 men and 531 women in Göteborg suggested a 5 to 10% increase per 5-year period. Generally, higher prevalence was observed in women than in men, and about 10% of the men and 20% of the women might have been asymptomatically infected.