Objectives: To compare tympanostomy tube insertion for children with otitis media in 2002 with the recommendations of two sets of expert guidelines. Design: Retrospective cohort study. Setting: New York metropolitan area practices associated with five diverse hospitals. Participants: 682 of 1046 children who received tympanostomy tubes in the five hospitals for whom charts from the hospital, primary care physician, and otolaryngologist could be accessed. Results: The mean age was 3.8 years. On average, children with acute otitis media had fewer than four infections in the year before surgery. Children with otitis media with effusion had less than 30 consecutive days of effusion at the time of surgery. Concordance with recommendations was very low: 30.3% (n=207) of all tympanostomies were concordant with the explicit criteria developed for this study and 7.5% (n=13) with the 1994 guideline from the American Academy of Pediatrics, American Academy of Family Medicine, and American Academy of Otolaryngology - Head and Neck Surgery. Children who had previously had tympanostomy tube surgery, who were having a concomitant procedure, or who had "at risk conditions" were more likely to be discordant. Conclusions: A significant majority of tympanostomy tube insertions in the largest and most populous metropolitan area in the United States were inappropriate according to the explicit criteria and not recommended according to both guidelines. Regardless of whether current practice represents a substantial overuse of surgery or the guidelines are overly restrictive, the persistent discrepancy between guidelines and practice cannot be good for children or for people interested in improving their health care.