BACKGROUND: Surgical removal of the tonsils (tonsillectomy) is a common but controversial ENT operation. OBJECTIVES: To determine the effect of tonsillectomy in patients with chronic/recurrent acute tonsillitis. SEARCH STRATEGY: Cochrane Controlled Trials Register, Medline, Embase, bibliographies. SELECTION CRITERIA: Randomised controlled trials comparing tonsillectomy with non-surgical treatment in adults and children with chronic/recurrent acute tonsillitis. Trials which included reduction in the number and severity of tonsillitis and sore throat as main outcome measures. DATA COLLECTION AND ANALYSIS: Two authors applied the inclusion/exclusion criteria independently. MAIN RESULTS: No trials evaluating the effectiveness of tonsillectomy in adults were identified. Two trials from Pittsburgh assessed tonsillectomy in children. Significant baseline differences between the surgical and non-surgical groups and the inclusion of children who also underwent adenoidectomy prevent firm conclusions being drawn from the fully published trial. Limited and insufficient information is available from the second study; further details are awaited. REVIEWER'S CONCLUSIONS: The effectiveness of tonsillectomy has not been formally evaluated. Further trials addressing relevant outcome measure are required.