Background: To determine the effect of single dose of intravenous dexamethasone (0.15 mg/kg) given at the time of induction of general anaesthesia for tonsillectomy in paediatric patients on post-operative nausea vomiting, pain and quality of oral intake. Materials And Methods: After ethical committee approval and parental consent, 64 children of ASA physical status I or II, aged 6 –16 years, scheduled for elective tonsillectomy with or without adenoidectomy, were randomly assigned to one of two groups to receive, at the time of induction of anaesthesia, either a single dose of intravenous dexamethasone (0.15 mg/kg) diluted in normal saline to total volume of 5 ml or an equal amount of normal saline. The post-operative pain scores were assessed at different time intervals post-operatively using objective pain scale and visual analogue score. Post-operative nausea and vomiting scores were assessed 30 mins, 3 hours, 6 hours, 12 hours, 24 hours post-operatively using Bellville PONV score. Quality of oral intake was assessed 3 hours post-operatively. Results: The demographic data were comparable between two groups. Post-operative pain scores and post-operative nausea and vomiting scores were significantly less in the dexamethasone group (study group) at different time intervals (p value<0.05). The number of patients who received rescue analgesia in study group and control group were 5 out of 32 and 13 out of 32 respectively (p=0.034). The need of rescue anti emetic in study group and control group were 25% and 46.9% respectively (p=0.048). At 3 hours post operatively, 21.9% in study group and 6.3% in control group had excellent quality of oral intake (p=0.022). Conclusion: Single intravenous dose of 0.15 mg/kg of dexamethasone given following induction of general anaesthesia in paediatric patients undergoing elective tonsillectomy with or without adenoidectomy reduces incidence of post-operative nausea and vomiting, provides better and prolonged post-operative pain relief and results in better quality of oral intake without side effects.