Otitis media (OM) is prevalent among preschool children. Boys have a higher incidence than girls. The seasonal variation of OM is parallel to that of upper respiratory infection. After the onset of acute infections, the effusions disappear at a rate of 40% at 2 weeks, 60% at 1 month, 80% at 2 months, and only 10% of the effusions last more than 3 months. The common risk factors are: sibling history of OM, victims of atopy and cleft palate, early onset of the first episode, and attendance in day care centers. Otitis-pronechildren should receive intensive follow-up examination, and their underlying diseases should be treated more aggressively.