Primary teeth are interesting models that can be used to study physiological and pathological processes involving cells and extracellular matrices in hard and soft tissues. This study investigated the expression and distribution of biglycan and decorin-the non-collagenous components of the extracellular matrix-in primary teeth tissue, during physiological root resorption. Thirty healthy human primary teeth were grouped together according to root length: Group I - two-thirds root length, Group II - one-third root length, and Group III - teeth with no root. The streptavidin-biotin-peroxidase immunohistochemical method was used with antibodies against the previously named antigens. The proteoglycans studied were found in the pulp and dentin extracellular matrix in all groups without any differences in the proteins, among the groups. Biglycan was observed mainly in predentin and in pulp connective tissue in the resorption area. In addition, decorin was observed mainly in pulp connective tissue, but near the resorption area. Biglycan and decorin were distributed differentially in the dental tissues. The present immunohistocytochemical data, combined with previously reported data, suggest that these proteoglycans could be involved in regulating the physiological resorption process in healthy primary teeth.