In a German seroepidemiological study to determine the proportion of pregnant women infected with herpes simplex virus type 2 (HSV-2) and at risk of transmitting the infection to the newborn during delivery, IgG antibodies to HSV-2 in 1999 sera collected from pregnant women in 1996-1997 were measured using an automated type-specific enzyme immunoassay (Cobas Core HSV-2 IgG EIA; Roche Diagnostics, Switzerland). The seroprevalence of HSV-2 was 8.9%, and control studies with a type-common HSV assay measuring antibodies to HSV-1 and HSV-2 revealed that 20.7% of pregnant women were seronegative for HSV antibodies and are therefore at risk of acquiring primary genital HSV infection of either type.