The inherited forms of craniosynostosis can be divided into 4 groups: isolated craniosynostosis, craniosynostosis with syndactyly, craniosynostosis with polydactyly and syndactyly, and craniosynostosis with other somatic abnormalities. Acrocephalopolysyndactyly or Carpenter syndrome consists of craniosynostosis, short fingers, soft tissue syndactyly, preaxial polydactyly, congenital heart disease, hypogenitalism, obesity, and umbilical hernia. As many as three-fourths of the patients have some degree of intellectual impairment. The etiology of mental retardation in this syndrome has not been explored. A patient is reported with the features of Carpenter syndrome who has profound developmental delay and cerebral malformations demonstrated by magnetic resonance imaging and computed tomography. Because mental retardation is not an invariable feature of this syndrome or other craniosynostosis syndromes, neuroradiologic examination may help in predicting the intellectual outcome in these patients.