Studies are reported on 3 patients with hereditary ectodermal dysplasia. With the exception of the family described by Darwin,¹ this is apparently the first report of the affliction occurring in three members of one family in the same generation. Special studies on these persons include serum analyses and observations on the effect of exposure to high environmental temperatures.

The literature pertaining to hereditary ectodermal dysplasia has been reviewed by MacKee and Andrews,² Weech,³ Gordon and Jamieson,⁴ Lord and Wolfe,⁵ de Silva⁶ and others. In 1929 Weech listed 10 cases of this unusual condition; in 1931 Gordon and Jamieson listed 21 cases, and more recently, in 1938, Lord and Wolfe tabulated in chronologic order more than 40 cases described in the literature together with a bibliography pertaining to them.

The salient features of the disease are: the absence of sweat glands and occasionally of lacrimal glands; the growth of