A 21-year-old man with acute retinal necrosis showed a marked increase in the convalescent titer to herpes simplex type 1 virus, especially in the aqueous humor obtained by anterior chamber paracentesis. Using an enzyme-linked immunosorbent assay, we tried to detect the herpesvirus antigen in the circulating immune complex obtained from this patient. The immune complex contained an antigen or antigens that reacted with antiherpes simplex type 1 antibody.