Forty-five infants with myelomeningocele in whom hydrocephalus was absent or adequately controlled developed signs and symptoms of the Arnold-Chiari malformation before the age of 3 months. All of them underwent laminectomy and opening of the dura mater for hindbrain decompression. The clinical presentation included swallowing difficulty, apneic episodes, stridor, bronchial aspiration, arm weakness, and opisthotonos. Within 2 weeks of the initial clinical presentation, the neurological status of 14 patients (31%) deteriorated dramatically and culminated in irreversible neurological deficits. In all patients, compression of the brain stem occurred in the spinal canal. A transverse dural band constricting the dural sac at the C-1 level was noted in 41% of the patients, and a mild degree of arachnoidal adhesion was noted in 23%. The lowermost level of the cerebellar tongue or medullary kink was located at C-1 to C-4 in 28 cases and at C-5 to T-1 in 17 cases. Twenty-eight (62%) of the patients were alive and 17 (38%) had died at the last follow-up assessment. All survivors showed improvement of their overall neurological function. Twenty-four made a complete recovery. The majority of deaths were attributed to respiratory failure. Early recognition of symptoms and prompt decompressive laminectomy are essential for successful management of the Arnold-Chiari malformation in infants.