Periodontal conditions and salivary levels of immunoglobulins sIgA, IgM, and IgG subclass distribution and albumin, quantified by enzyme-linked immunosorbent assay, were determined in 20 patients with Down syndrome and 19 healthy controls. Gingival inflammation was more extensive (P < 0.05) among Down syndrome subjects compared to controls as well as the occurrence of periodontal pockets (> 4 mm) (P < 0.05). The Immunoglobulin levels of sIgA, IgM, the sum of IgG subclasses, and the concentration of albumin did not differ significantly between the 2 groups. However, the proportion of IgGl expressed as percentage of the sum of total IgG was significantly higher (P < 0.01) in the Down syndrome group compared to controls. On the contrary, the proportion of IgG2, IgG3, and IgG4 subclasses in saliva did not differ between the 2 groups. The results indicate an altered distribution of IgG subclasses in saliva, with a higher proportion of IgGl in Down syndrome individuals compared to controls. J Periodontol 1998;69:1119-1123.