The ability of IgG anti-Fc and anti-Fab to neutralize infectious herpes simplex virus-IgG (HSV-IgG) complexes was determined. When limiting amounts of antiglobulin were used, antibody directed against the Fab portion of human IgG was significantly more effective than anti-Fc antibodies in neutralizing the HSV-IgG complexes. The detection of viral bound antibody was enhanced by the incorporation of heterologous antiglobulin or complement in the antiglobulin neutralization test. Specifically, HSV-IgG which had been incubated with rabbit antihuman globulin was further neutralized by goat antirabbit IgG or guinea pig serum complement. This augmented neutralization test could prove useful in detecting small amounts of antibody bound to virus in infectious isolates from patients or experimental animals with viral diseases.