Five years after publishing the document on 'The clinical and organizational appropriateness of tonsillectomy and adenoidectomy' in 2003, a multidisciplinary group of experts came together again to update this document and to publish a guideline with grading of evidences and recommendations. Major revisions of the previous document were addressed to: (1) the diagnosis and indications for adenotonsillectomy in presence of OSAS in children, (2) the analysis of advantages of new surgical techniques in terms of effectiveness, costs or the risk of postsurgery bleeding and recurrences, and (3) the efficacy of perioperative management in reducing the incidence and duration of post-operative events. In fact, in the last years, a relevant number of evidence became available on the above-mentioned items making the need for a continuing updating of guidelines tangible. As a premise to the guideline, it is stressed how the previous document impact was prominent: the decrease of total number of tonsillectomy in Italy was evident and accompanied by a decrease of variations in the regional rates. Besides the document contributed to strengthen the multidisciplinary collaboration, especially between pediatricians and otorhinolaryngologists, and to divulge the Evidence-Based Medicine culture.