Ectodermal dysplasia is a rare condition characterized by complete or partial anodontia and by defects in other ectodermal structures. Thoma, 1 in his textbook "Oral Pathology," has given a collective review of 18 cases reported in the literature from 1883 to 1941, and Brodie and Sarnat 2 contributed another case in 1942. REPORT OF A CASE History .—V. M., a girl born April 7, 1941, came under observation at the children's endocrine clinic on Jan. 28, 1944 at the age of 2 years and 8 months, having been referred from the children's clinic of the Boston Dispensary because of the peculiar behavior of her teeth and nails. The mother stated that neither finger nails nor toe nails ever grew; hence they were never cut. The patient neither complained of excessive heat nor suffered from spells of fever or syncope on exposure to the summer sun. She had never been sick