The distribution of fibronectin (FN) in the dental pulp and gingiva of the human adult was investigated by indirect immunofluorescence and indirect immunoperoxidase techniques. FN could not be demonstrated in the connective tissue of the dental pulp even in the blood vessels. On the contrary, a positive stain was obtained in the ground substance at the base of the odontoblast cell bodies and in various structures of a denticle which was accidentally found in the pulp of one of the examined teeth. The lack of FN in the dental pulp could mean that this tissue, sometimes considered to be of an immature and undifferentiated type, is instead a mature one. The subepithelial connective tissue and the epithelium of the gingiva were examined. The distribution of FN in the connective tissue of the gingiva was found to be similar to that described in other types of connective tissue; high concentrations were found both in the epithelial cells and around them. This finding is described here for the first time and remains to be verified in other types of stratified epithelia.