The prevalence of antibodies to CMV, Mumps and Coxsackie virus strains 1, 3 and 4 was studied in 39 samples of gingival crevicular fluids (GCF) obtained from clinical healthy patients and compared to the corresponding antibodies present in the serum of each individual. In spite of the high prevalence of humoral antibodies to CMV (75%), only 24% of the gingival crevicular fluid samples exhibited IgG or IgA antibodies to this virus. The differences in the prevalence of antibodies against Mumps virus in the sera and GCF were even greater: whereas 87% of the patients exhibited serum antibodies, not even a single gingival fluid sample was found to be positive. Antibodies to Coxsackie B strains 1, 3 and 4 were found in 72%, 63% and 52% of the sera and in 25%, 19% and 33% of the gingival fluid samples (IgG only). The presence of the antibodies and their profile in GCF and serum is different. The mechanism of possible permeation is not clear but it seems that viral antibodies in this milieu are not derived from the serum solely by passive transudation, and that the antibodies are produced locally at least in some of the GCF specimens.