Local immune factors may play a role in the protection against oral disease and defences against microflora may be related to immunoglobulin A (IgA) subclass responses. The objectives of this study were to determine the concentrations and ratios of salivary IgA and IgA subclasses in predentate and dentate children and adults and to compare the levels in breastfed and bottle-fed infants. Whole saliva samples were collected from: a) 44 predentate children (mean age 4 months), b) 29 dentate children (1.5 years) and c) 28 adults (29.5 years). Immunoglobulin levels were assayed by enzyne-linked immunosorbent assay using colostral IgA standard. In the predentate children, the mean IgA, IgA1 and IgA2 levels were lower than in the dentate group but the difference reached statistical significance with IgA2 levels only. The comparative concentrations in the adult group were significantly higher than that in both children's groups. The IgA1:IgA2 ratio was similar in all 3 groups, at approximately 58:42. No significant differences were found in the concentration of salivary IgA and IgA subclasses in the breastfed infants compared with the bottle-fed ones. The results of this investigation confirm other studies suggesting that the concentration of salivary IgA subclasses are not significantly different between predentate and dentate children and that they do not reach adult levels until well after 2 years of age.