Hereditary mucoepithelial dysplasia, a dyshesive, dyskeratotic epithelial syndrome caused by an abnormality in desmosomes and gap junctions, involves the mucosae, skin, hair, eyes, and lungs. A 16-year-old patient had nontender, fire-red mucosae; keratosis pilaris; diffuse, nonscarring alopecia; cataracts; photophobia; corneal vascularization; and decreased visual acuity. Histologic examination of gingival sections showed a dyshesive epithelium with atrophy, dyskeratosis, lack of keratinization, and unusual cytoplasmic inclusions. Results of electron microscopic studies showed a reduced number of desmosomes, amorphous intercellular material, and cytoplasmic inclusions resembling tonofilaments and gap junction material. The patient described in this report represents an apparently sporadic case of hereditary mucoepithelial dysplasia. Other cases described previously in the literature are reviewed. We believe this disorder should be brought to the attention of dermatologists because patients with hereditary mucoepithelial dysplasia have numerous skin problems and are susceptible to recurrent infection and potentially fatal bullous lung disease. Also, misinterpreted abnormal results from cervical Pap smears could lead to hysterectomy being performed unnecessarily on these patients.