Seventeen unrelated patients with multiple anomalies of unknown etiology were identified by the presence of choanal atresia. A regularly recurring pattern of associated features involving mental retardation, postnatal growth deficiency, hypogenitalism (males), small ears, cardiac defects, micrognathia, postnatal microcephaly, and ocular coloboma was identified. Choanal atresia when accompanied by multiple anomalies of unknown etiology has a serious prognosis with a predictable pattern of associated defects.