Background: Infections by herpes simplex viruses type 1 (HSV-1) and type 2 (HSV-2) are common in the United States. Herpes simplex virus type 2 is transmitted sexually, and the prevalence of antibodies to HSV-2 has increased in recent years. Goals of this Study: The objective of the present study was to estimate the seroprevalence of HSV-1 and HSV-2 antibodies among women attending a sexually transmitted disease (STD) clinic and to evaluate factors associated with HSV-1 and HSV-2 seropositivity. Study Design: The report describes a cross-sectional study conducted at an STD clinic. This study included 1,103 women between the ages of 18 and 35. Eighty-nine percent of the subjects were African Americans. The remaining subjects were white. Results: The overall prevalence of HSV-1 and HSV-2 antibodies among study subjects was 72% and 64%, respectively. Both HSV-1 and HSV-2 seropositivity were related directly to age and were higher among African Americans than whites. The prevalence of HSV-2 antibodies also increased with the number of lifetime sexual partners, an early age at first coitus, a history of syphilis, and the absence of HSV-1 antibodies. Drug use and recent use of barrier contraception were unrelated to either HSV-1 or HSV-2. Comment: Despite efforts by the public health community to prevent AIDS by promoting safe sexual practices, the prevalence of HSV-2 seropositivity has increased in recent years. Increased numbers of partners and an early age at first coitus are important correlates of HSV-2 infection. Public health interventions to prevent HSV-2 infection should target teenagers. Women of reproductive age attending STD clinics may also comprise an important target for interventions to prevent perinatal herpes.