Wentworth, B. B. (School of Public Health and Community Medicine, Univ. of Washington, Seattle, Wash. 98195) and E. R. Alexander. Seroepidemiology of infections due to members of the herpesvirus group. Amer J Epidem 94: 496–507, 1971.—Prevalence of complement-fixing antibodies to cytomegalovirus (CMV), herpes simplex virus (HSV) and varicella-zoster virus (VZV) were determined in 4824 sera from a predominantly middle class urban population, age 5 to 60 years. Prevalence of antibody to CMV and HSV was low in childhood and rose steadily with age, unlike that to VZV, which was highest in childhood and decreased with age. Females had a higher prevalence of CMV and HSV antibodies at all ages than did males, whereas this difference was seen only in ages less than 20 with VZV antigen. Although sera from either pregnant females or females with a history of pregnancy had a somewhat greater prevalence of antibodies to CMV and HSV than sera from nonpregnant females without a history of pregnancy, this increase was not sufficient to account for the difference between male and female rates. There was a significant association between the occurrence of antibodies to CMV and HSV which appeared to be due to common epidemiologic factors, since there was no demonstrable cross-reactivity between the antigens. Prevalence rates for this population appeared to occupy an intermediate position when compared with other published reports.