Middle ear ossicles removed during ear surgery in 40 patients were examined in order to compare the histopathologic changes in children with those observed in adults. Bone resorption, mainly localized at the level of the periosteum and haversian canals in adults, was much more extensive in children. Replacement of bone by fibrous granulation tissue was observed in 60% of children's ossicles and in 27% of those belonging to adults. In children, extensive active resorptive osteitis of the ossicles was frequently associated with intensive round cell infiltration, which seems to play an important role in bone absorption and in the aggressiveness of cholesteatoma.