Tumoral calcinosis (TC) is a rare inherited autosomal dominant metabolic disease manifested by elevated serum phosphorus and 1,25 dihydroxyvitamin D levels and periarticular cystic and solid tumorous calcifications. The dental findings in a large family have been critical in determining the genetic transmission of the condition. Radiographically the teeth have short bulbous roots, pulp stones and partial obliteration of the pulp cavity. Histologically, coronal dentin and a variable amount of radicular dentin appears to be deposited regularly. At nonspecific points the developing radicular dentin appears to encounter a mass of calcified material and proceed to grow around it. This mass has a unique histologic pattern with ovoid spaces surrounded by amorphous calcification. At levels of further root development the radicular dentin has an irregular bending tubule arrangement. The dental lesion of TC appears to be different from that of radicular dentin dysplasia in histologic structure and in the method of initiation of the dentin defect. These data suggest that the specific dental lesion is a new phenotypic marker for TC.