In a prior systematic community survey, 20 adults were found to have antibodies to viral capsid antigen (VCA) and early antigen (EA) OF Epstein-Barr virus (EBV) in serum. The presence of the latter antibody suggested a recent response to EBV. In the present study the significance of antibody to EA was more extensively evaluated by examination of the sera of these adults for the presence of EBV-specific IgM antibodies (EBV-IgM) and antibodies to EBV nuclear antigen (EBVNA). Sera of a matched group of adults with antibodies to VCA but without antibodies to EA were compared with those of the 20 adults with antibodies to EA (anti-EA-positive). In the anti-EA-positive group, 19 specimens of serum contained EBV-IgM, 16 contained elevated titers of antibodies to VCA, and 20 contained antibodies to EBVNA. The sera of the matched group had neither detectable EBV-IgM nor elevated titers of antibodies to VCA; however, all sera had antibodies to EBVNA. None of the individuals gave a history of an infectious mononucleosis-like illness. It was suggested that the majority, if not all, of the anti-EA-positive group were manifesting a host immune response to endogenous reactivation of latent EBV. It is of interest that the presence of EBV-IgM was part of this response.