A major sequelae of impacted cerumen (earwax) is conductive hearing loss, which can be deleterious to linguistic, social, and intellectual development, particularly for individuals with mental retardation. The longitudinal incidence (12-year period) of excessive/impacted cerumen and related conductive hearing loss of 117 adults with mental retardation was examined. Results indicated a considerably higher incidence of excessive cerumen and cerumen impaction with associated conductive hearing loss in adults with mental retardation (28%) than in the general adult population (2% to 6%). Moreover, a strong propensity for recurrent cerumen impaction in the mentally retarded population was found. These findings were discussed in view of the management of cerumen impaction among individuals with mental retardation.