Fifty-seven children were seen over a 10-year period, 1984-1994, at two large pediatric referral centers with a diagnosis of mastoiditis. Twelve had acute infection and 45 had chronic manifestations. Clinical presentations and recovered bacterial pathogens were identical to those reported in earlier literature although the incidence of both acute and chronic mastoiditis has decreased markedly since 1950. The availability of computed tomographic (CT) scans during this decade has improved the management of chronic disease by defining the location of cholesteatomas and the extent of disease as well as possible anatomic variations and potential complications encountered during surgery. CT scanning is indicated in acute disease when there is suspicion of chronic suppuration or destruction of the mastoid.