Herpes simplex virus (HSV) is a member of the Herpesviridae family, of which two types are known: type 1 (HSV-1) and type-2 (HSV-2) which present slight antigenic differences. The assay of specific IgG is important to establish the serological state of the patient, diagnosis of neonatal infection and encephalitis caused by HSV. Moreover, the presence of specific IgG indicates viral activity in progress, although it is not possible to distinguish between primary infection and reactivation.