Introduction: The effectiveness of dexamethasone (DEX) in reducing complication rates following paediatric tonsillectomy is still up for debate. The incidence of postoperative nausea and vomiting (PONV) and the severity of pain following paediatric tonsillectomy were examined by comparing concentrations of DEX 0.15 and DEX 0.5 mg/kg, respectively. Aim of the study: The aim of the study is to assess the effect of Dexamethasone in management of postoperative nausea, vomiting and pain after tonsillectomy where the targeted patients are of 3 to 10 years children. Methods: This prospective cross sectional study was conducted in the Department of Paediatric Anaesthesiology and Surgical ICU in Bangladesh Shishu Hospital and Institute, Dhaka, Bangladesh during July 2019 to June 2022. This study included 123 children undergoing elective tonsillectomy. The Institutional Ethics Committee approved this study and informed parental written consent was obtained from the parents before collecting the patients’ information. Results: The prevalence of early PONV was lower in both DEX groups (DEX 0.15: 22%; DEX 0.5: 26%; placebo: 48%; P=0.001). On the second day after surgery, the DEX groups had a lower rate of severe pain (DEX 0.15: 20%; DEX 0.5: 5%; placebo: 47%; P<0.001). The study was not conducted to assess a difference between the two dose groups of Dexamethasone. Conclusions: The frequency of early and late PONV and the level of pain on the second postoperative day were both reduced by an i.v injection of DEX during the induction of anesthesia. To reduce the incidence of PONV, it appeared that a dose of DEX 0.15 mg/kg was just as effective as a dose of DEX 0.5 mg/kg.