BackgroundNeither the incidence of indications for childhood tonsillectomy nor the proportion of tonsillectomies that are evidence-based is known.AimTo determine the incidence of indications for tonsillectomy in UK children, and the proportion of tonsillectomies meeting evidence-based criteria.Design and settingA retrospective cohort study of electronic medical records of children aged 0–15 years registered with 739 UK general practices contributing to a research database.MethodChildren with recorded indications for tonsillectomy were identified from electronic medical records. Evidence-based indications included documented sore throats of sufficient frequency and severity (Paradise criteria); periodic fever, aphthous stomatitis, pharyngitis, and cervical adenitis syndrome (PFAPA); or tonsillar tumour. Other indications were considered non-evidence-based. The numbers of children subsequently undergoing tonsillectomy was then identified. The numbers with evidence-based and non-evidence-based indications for surgery among children who had undergone tonsillectomy were determined.ResultsThe authors included 1 630 807 children followed up for 7 200 159 person–years between 2005 and 2016. Incidence of evidence-based indications for tonsillectomy was 4.2 per 1000 person years; 13.6% (2144/15 760) underwent tonsillectomy. Incidence of childhood tonsillectomy was 2.5 per 1000 person years; 11.7% (2144/18 281) had evidence-based indications, almost all with Paradise criteria. The proportion of evidence-based tonsillectomies was unchanged over 12 years. Most childhood tonsillectomies followed non-evidence-based indications: five to six sore throats (12.4%) in 1 year, two to four sore throats (44.6%) in 1 year, sleep disordered breathing (12.3%), or obstructive sleep apnoea (3.9%).ConclusionIn the UK, few children with evidence-based indications undergo tonsillectomy and seven in eight of those who do (32 500 of 37 000 annually) are unlikely to benefit.