Dental enamel hypoplasia is a constant and pathognomonic sign in patients with TS. The defect consists in small cavities (pits) that measure average 80 microns and affect only the enamel without producing lesion to the dentin. We studied the morphology of retained dental pieces of three patients with TS. The pits showed conical and cylindrical shape and measured from 50 to 500 microns. The identification of enamel hypoplasia in deciduous and permanent teeth is of a great value for early diagnosis when other anomalies of TS are not yet produced.