Apert-Crouzon syndrome (formerly ACS type 2; 10130) is now considered a subset of autosomal dominant Apert acrocephalosyndactyly type 1 (10120), with features of craniosynostoisis, syndactyly of all extremities, maxillary hypoplasia, "parrot-beaked" nose, hypertelorism, exophthalmos, external strabismus, and short upper lip. We report a 3 1/2-month-old infant with features of Apert syndrome, plus thoracic vertebral anomalies radiographically similar to those seen in spondylothoracic dysplasia, a condition in which block thoracic vertebrae with widely open neural arches and a fan-shaped thoracic cage are found. Our patient also had flared metaphyseal ends of humeri, dislocated radii with immobile elbows, an unusual tail-like protuberance in the coccygeal area, and a solid cartilaginous tracheal wall. To date, in ongoing reviews of radiographs of other patients with acrocephalosyndactyly or acrocephalopolysyndactyly complexes and of relevant literature, we have not identified other patients with these findings. The vertebrae and intervertebral discs of the patient in this report, three patients with Jarcho-Levin syndrome, and one with Apert syndrome were measured from anteroposterior chest radiographs; the findings clearly distinguish the condition in our patient from Jarcho-Levin syndrome or Apert syndrome.