We conducted a prospective, observational study over a 3-year period to compare the clinical, functional, and surgical findings in children with chronic bilateral otitis media with effusion who underwent one of three different types of treatment. Our study population was made up of 150 patients-79 boys and 71 girls aged 24 to 84 months-who were randomly assigned to one of the three treatment groups of 50 patients each. One group was treated with myringotomy, tympanostomy tube insertion, and adenoidectomy (T+A group); another with a combination of physical conservative treatment and adenoidectomy (P+A group); and the third with physical conservative treatment alone (P-only group). Hearing levels and tympanogram trends were evaluated during a follow-up of 12 months. In the T+A group, we noted a stable normalization of hearing in 95 of the 100 ears. Treatment with the P+A combination resulted in an improvement of hearing in 79 ears, but the improvement was maintained in only 27 ears during 12 months of follow-up. In the group with the P-only regimen, an amelioration of hearing was registered in 76 ears, but it was unstable in all cases. A type A tympanogram was maintained during the follow-up period for 2 ears in the P+A group and for 4 ears in the P-only group. Myringotomy with a detailed examination of the tympanic cavity in all ears with prolonged abnormal audiologic results revealed that types C and B tympanograms, which were found in most ears in the P+A and P-only groups, corresponded to middle ear chronic inflammatory changes (retraction pockets, granulations, adhesions, etc.) Based on our findings, we conclude that the use of a physical conservative treatment with or without an adenoidectomy does not prevent the development of chronic adhesive and purulent otitis media.