We present a polysomnogram-documented report of central sleep apnea (427 events) and moderately severe decreases in arterial oxygen saturation (to 81%) associated with the Arnold-Chiari malformation (ACM). Daytime hypersomnolence and other symptoms had significantly impaired our patient's work performance. After surgical correction of the ACM, there was marked improvement in symptomatology. A post-surgery polysomnogram revealed marked improvement in the number of central apneas (74 events) and only mild decreases in oxygen saturation (to 94%).