We used the Hospital Episodes Statistics database to investigate unwarranted variation in the rates Trusts discharged children the same day after scheduled tonsillectomy and associations with adverse postoperative outcomes. We included children aged 2-18 years who underwent tonsillectomy between 1 April 2014 and 31 March 2019. We stratified analyses by category of Trust, non-specialist or specialist, defined as without or with paediatric critical care facilities, respectively. We adjusted analyses for age, sex, year of surgery and aspects of presentation and procedure type. Of 101,180 children who underwent tonsillectomy at non-specialist Trusts, 62,926 (62%) were discharged the same day, compared with 24,138/48,755 (50%) at specialist Trusts. The adjusted proportion of children discharged the same day as tonsillectomy ranged from 5% to 100% at non-specialist Trusts and 9% to 88% at specialist Trusts. Same-day discharge was not independently associated with an increased rate of 30-day emergency re-admission at non-specialist Trusts but was associated with a modest rate increase at specialist Trusts; adjusted probability 8.0% vs 7.7%, odds ratio (95%CI) 1.14 (1.05-1.24). Rates of adverse postoperative outcomes were similar for Trusts that discharged >70% children the same day as tonsillectomy compared with Trusts that discharged <50% children the same day, for both non-specialist and specialist Trust categories. We found no consistent evidence that day-case tonsillectomy is associated with poorer outcomes. All Trusts, but particularly specialist centres, should explore reasons for low day-case rates and should aim for rates >70%.