Four individuals from 2 generations of a family had a hidrotic type of ectodermal dysplasia (ED). Males and females were similarly affected. They had trichodysplasia, with absent eyebrows and eyelashes; normal teeth, onychodysplasia; normal sweating; mild retrognathia; abnormal dermatoglyphics; and mental retardation. Additional variable manifestations included irregular menses, high implanted or prominent ears, café-au-lait spot, keratosis pilaris, supernumerary nipple, and mild hearing loss. Their previously undescribed condition could be classified as an ED of 1-3 (trichoonychial) subgroup of group A according to Freire-Maia's classification and is inherited as an autosomal recessive trait.