Abstract: Two cases of X-linked recessive anhidrotic ectodermal dysplasia(A.E.D.)were reported.The perspiration functions were tested in the two patients. It was demonstrated thet when the environmental temperature was above 35℃ the regulation of body temperature was completely disturbed due to the absence of sweat gland. The temperature of skin rose in direct proportion with a rise in environments)temperature.However, the temperature of the rectum was relatively stable. Therefore patients were able to regulate the body temperature by means of insensible perspiration but the amount was only one fourth as compared with normal persson.A bsence of sweat gland was further demonstrated through the examination of the function of autonomic nervous system. No electroreflex of skin could be observed to the needle touch, but the language stimulation induced a weak electroreflex of the skin that suggested the cutaneous electroreflex was mainly based on the existence of sweatregland but that is not the only basis.