Purpose of this prospective, double-blind, parallel-group, placebo-controlled, randomised clinical trial was to confirm our hypothesis that ramelteon has a preventive effect on emergence agitation after general anaesthesia in children. Patients aged 18 to 119 months (ASA physical status 1 or 2), scheduled to undergo tonsillectomy under general anaesthesia, were randomly allocated to the ramelteon or placebo group. Before general anaesthesia induction, patients in the ramelteon group received 0.1 mg kg−1 of ramelteon dissolved in 5 mL of lactose-containing syrup. The patients in the placebo group received the same amount of syrup alone. The Paediatric Anaesthesia Emergence Delirium score was calculated every 5 min after awakening. The primary outcome was the incidence of emergence agitation (Paediatric Anaesthesia Emergence Delirium score ≥ 10). Paediatric Anaesthesia Emergence Delirium scores, post-operative vomiting incidence, pain scores, and adverse events were secondary outcomes. Fifty patients were enrolled. Forty-eight patients were analysed. There was no significant between-group difference in the incidence of emergence agitation (67% in both groups; risk ratio, 1.0; 95% CI 0.67–1.49; P > 0.99) or any of the secondary outcomes. Our results suggest that 0.1 mg kg−1 of ramelteon does not have a preventive effect on emergence agitation after general anaesthesia in children undergoing tonsillectomy.