OBJECTIVE Craniosynostosis is a devastating disorder characterized by premature closure of the cranial plates before or shortly after birth. This results in an abnormally shaped skull, face, and brain. Little is known about hearing disorders in such patients, and nothing has been published about their auditory brainstem responses. Our objective was to evaluate such patients for auditory brainstem response and hearing disorders with the long-term goal of improving patient evaluation and management. METHODS We evaluated the auditory brainstem responses, hearing, and brain images of children with fibroblast growth factor receptor 2 craniosynostosis (n = 11). RESULTS Prolongation of the auditory brainstem response I-to-III interpeak latency was a frequent characteristic of fibroblast growth factor receptor 2 craniosynostosis, occurring in 91% of our patients. Prolongation of the III-to-V interpeak latency was an occasional characteristic, occurring in 27% of our patients. Whenever the I-to-III interpeak latency was prolonged, wave II was always abnormal. Associated morbidities included sensorineural hearing loss (27%), recurrent otitis media (100%), and Arnold-Chiari malformation (27%). Cranial decompression improved the interpeak latencies of 2 children. CONCLUSIONS These previously undocumented auditory brainstem response abnormalities reflect abnormal neural transmission, which could cause peripheral and central auditory processing disorders. We speculate that the major pathogenic basis of the I-to-III interpeak latency and wave II abnormalities is compression of the auditory nerve as it passes through the internal auditory meatus and posterior fossa, which would explain the auditory nerve hearing loss, tinnitus, and vertigo that affect these children. Awareness of these abnormalities could lead to important advancements in the auditory and neurosurgical assessment and management of this overlooked patient group. We provide recommendations for the improved assessment and management of these patients. In particular, we recommend that auditory brainstem response diagnostics become standard clinical care for this patient group as the best way to detect auditory nerve compression.