The effect of atopy (familial allergy) on the relationship of some craniofacial structures was studied cephalometrically in 100 11-year-old school-children. Seventeen children with neither atopy nor enlarged adenoids formed a control group. The atopic children were divided into three groups, those with moderate to severe atopy, those with mild atopy and those with possible atopy. The size of the adenoids was determined from lateral skull radiographs. In moderate or severe nasal allergy there was a dorsal rotation of the mandibular body and an anterior lowering of the nasal floor. The findings were similar to those seen in children with enlarged adenoids. The difference was more pronounced between the control group and the children with atopy and enlarged adenoids.