A primary infection with CMV protects women against acquiring a second CMV infection from an infected child. Because exposure occurs at oral mucosal surfaces and because the majority of the neutralizing activity is against CMV glycoprotein B (gB), we determined the levels of mucosal antibodies to CMV gB in healthy adults. 10 seronegative subjects lacked IgG and sIgA in parotid saliva (ps) and nasal washes (nw). For 10 seropositive adults: 10 had IgG to gB in ps and 7 in nw and 7 had low levels of sIgA. Among 12recipients of a live CMV vaccine (Towne), 8 had IgG antibodies to gB in either ps or nw collected between 10 and 20 months after immunization and 4 had sIgA to gB in nw. All 10 recipients of a purified gB vaccine in adjuvant MF/59 had IgG to gB in both ps and nw collected just before and one month after a 2nd booster and 5 had detectable levels of sIgA gB in both ps and nw. Both the concentration of IgG to gB and neutralizing titers in serum correlated linearly with the amounts of IgG to gB in ps and nw. IgG to gB was detected in the ps of 25 of 26 subjects with serum neutralizing titers of>1:64 but in only 6 of 9 ps samples from subjects with neutralizing titers of≤1:64 (P = 0.044). Serum neutralizing titers >1:64, whether induced by vaccine or wild type virus, will produce mucosal antibodies to gB that may protect against CMV infection.