We report a case of X-linked alpha-thalassemia/mental retardation syndrome (ATR-X) with repeated apnea attacks dating from the patient's 12th year. We initially diagnosed them as obstructive apnea due to upper pharyngeal stenosis and laryngomalacia by polysomnography and laryngo-fiberscopy. However, reevaluation after one and a half years revealed that the boy had central and mixed apnea, as well as obstructive apnea. To date, few reports have been published on the causes of apnea attacks in ATR-X patients. We clinicians should therefore consider laryngomalacia as one cause of apnea attacks in ATR-X patients, and choose the appropriate therapy for a pattern of apnea that can change during its clinical course.