The mucopolysaccharidoses are rare, genetically transmitted metabolic disorders that affect children early in life. These potentially life-threatening diseases almost invariably involve the auditory apparatus and the upper respiratory tract. Thus, the otolaryngologist is frequently involved in the care of these patients. This paper presents a 10-year retrospective review of the management of these patients at the Hospital for Sick Children. Data concerning auditory and upper respiratory pathology are presented. Results indicate that persistent serous otitis, sensorineural hearing loss, and upper respiratory obstruction leading to sleep apnea, are frequent findings in these patients. Specific recommendations are made with regard to appropriate otolaryngologic intervention in children affected with these diseases.