Allergies related to dentistry generally constitute delayed hypersensitivity reactions to specific dental materials. Although true allergic hypersensitivity to dental materials is rare, certain products have definite allergenic properties. Extensive reports in the literature substantiate that certain materials cause allergies in patients, who exhibit mucosal and skin symptoms. Currently, however, neither substantial data nor clinical expe rience unequivocally contraindicate the discontinuance of any of the materials, which include dental amalgam and nickel-and chromium-containing metals. The dentist forms a vital link in the team approach to the differential diagnosis of allergenic biomaterials that elici stymptoms in a patient, not only intraorally, but also on unrelated parts of the body.