Antibodies to cytomegalovirus (CMV), Epstein-Barr virus (EBV), and herpes simplex viruses types 1 and 2 (HSV-1, HSV-2) in three sequential serum samples from 62 men who did and 61 men who did not develop human immunodeficiency virus (HIV) infection at the time of the final (third) serum specimen were studied. Antibody titers to CMV, EBV, and HSV-1 did not significantly rise in or differ between men who did or did not get HIV infection. However, we found that 32 (68%) of 47 HIV seroconverters had antibodies to HSV-2 at the time the third specimen was drawn, whereas only 26 (46%) of 57 men who remained HIV seronegative had HSV-2 antibody positivity. Seroconversion to HSV-2 between any two serum specimens was found in 11 (42%) of the 26 HIV seroconverters but in only five (14%) of 35 men who remained HIV seronegative. The association between HSV-2 seropositivity (or seroconversion) and subsequent or concurrent HIV seroconversion remained when we controlled for factors known to influence HIV infection, including age, number of sexual partners, and percentage of sexual acts involving receptive anal intercourse. These serologic studies do not support the role of CMV, EBV, or HSV-1 in HIV infection but do suggest that HSV-2 infection is a risk factor for subsequent or concurrent HIV infection.