Otitis media (OM) is a common disease in children. The present study was designed to characterize the onset, duration and frequency of acute otitis media (AOM), and otitis media with effusion (OME) in the first 2 years of life. 306 children were enrolled at birth. 70% of the children experienced≥1 episodes of OM (46% AOM, 24% OME) by 1 yr. and 85% (57% AOM, 28% OME) by 2 yrs. First episodes of AOM (mean age 5.2 mos.) occurred earlier than OME(mean age 6.3 mos.), p<.01. Peak crude monthly incidence of OM, 33%, occurred between 15 and 18 mos. Mean numbers of episodes of AOM at 1 and 2 years of age were 1.5 and 2.1, respectively; 5% of the population who experienced ≥4 episodes of AOM by 1 year or ≥5 episodes by 2 years were classified as otitis prone. Mean numbers of episodes of OME at 1 and 2 years were 1.3 and 1.5, respectively. 66% of first episodes of AOM resolved ≤ 1 month compared to 53% for OME. With succeeding episodes, duration decreased for AOM but increased for OME. Mean duration for first episodes of AOM and OME were 1.5 mos. and 1.9 mos., respectively, compared to 2.1 mos. and 1.3 mos. for third episodes. Total time spent with OM increased from a mean of 3.3 mos. to 4.5 mos. from the first to second year. These data suggest that AOM and OME are both common entities and that the total time spent with middle ear disease may be substantial during infancy.