A case review of a healthy 3-year-old toddler with a chief complaint of sleep-disordered breathing is presented. The child underwent a pneumogram sleep study with significant abnormal findings. Magnetic resonance imaging led to a diagnosis of Arnold-Chiari type I malformation and the need for posterior fossa decompression. The child has been monitored, and 1 year postoperatively, her sleep apnea has resolved and day-time function and development remain normal. Definitions of the different types of Arnold-Chiari malformation are discussed, with sleep apnea presenting as the only symptom. The importance of a sleep history as part of the practitioner's pediatric assessment is explored.