Acute otitis media (AOM) and otitis media with effusion (OME) are very common in the young children. The relation ship between these two pathologies has not been completely established. The AOM incidence ranges between 22 to 74%. The OME which persists after onset of AOM is more frequent (20% at 2 months) than the chronic OME which concern 4.4 to 10% of the child population before the age of five. The highest age specific incidence for all episodes of AOM is one year of age. AOM and OME are most likely to occur in the winter. The OME risk factors are: the first episode of OMA before 6 month of age, the males sex, no breastfeeding, day-care centers, low socio-economic conditions and familial genetic predisposition. Passive-smoke exposure and allergy are discussed. The epidemiology assesses the actual state of these pathologies to settle, with the family, the optimum choices for the prevention.