Because antibodies against human cytomegalovirus (HCMV) glycoprotein B (gB) neutralize, levels of IgG, secretory IgA (sIgA), and mucosal IgA1 antibodies to HCMV were measured in saliva and nasal washes. Ten seronegative adults lacked these antibodies, but of 10 naturally seropositive adults, 10 had IgG to gB, 5 had sIgA, and 0 had mucosal IgA. Among 12 recipients of a live HCMV vaccine, 8 had IgG to gB, 4 had sIgA, and 2 had mucosal IgA in samples collected 10-20 months after immunization; of 10 recipients of a gB vaccine, 8 had IgG to gB, 7 had sIgA, and 7 had mucosal IgA in samples collected just before or 1 month after a booster. IgG to gB and neutralizing titers in serum correlated with IgG to gB in mucosal samples. IgG to gB was in the saliva of 25 of 26 subjects with serum neutralizing titers > 1:64. Serum neutralizing titers > 1:64, whether induced by vaccine or wild type virus, are associated with mucosal IgG to HCMV.