Recent studies have indicated possible changes in the incidence of acute mastoiditis. A retrospective review of children discharged with a diagnosis of acute mastoiditis was undertaken to describe the epidemiology, clinical presentation, microbiology, and treatment of acute mastoiditis over past years. Demographic historic, clinical, and laboratory data were collected. Eighty-six children (88 episodes of acute mastoiditis) were identified (1 month-16 years) (median 3.3 years). Almost half had a history of middle ear disease; 8% recurrent episodes and 68.2% received antibiotics preadmission, 91.2% for acute otitis media. Bacterial etiology was established in 43 patients (68.2% isolation rate). Pseudomonas aeruginosa and Streptococcus pneumoniae were the most frequently isolated agents. This review showed a significant increase (150%) in the number of patients with acute mastoiditis.