Characteristics of ectodermal dysplasia and agammaglobulinemia have been presented and a case in a 6 1/2-year-old boy having both genetic diseases is reported. The child had been mocked by his peers at school. A maxillary overlay denture and mandibular cast denture were constructed using a Baker bar and cast gold thimble crowns. The parents reported that the patients personality changed favorably after dental treatment was completed. He is now 13 years of age, has had his dentures replaced once, and enjous a rather active life with the aid of antibiotics and supplemental globulins.