Management of postoperative pain and emergence agitation following adenotonsillectomy in pediatrics has been a major challenge for anesthesiologists. Although analgesic sparing effect of ketamine has been studied during tonsillectomy in pediatrics, there is a lot of controversy about its efficacy. Present study was designed to evaluate the effect of intravenous low dose ketamine (0.25 mg/kg) during induction of anesthesia on postoperative pain and emergence agitation following adenotonsillectomy in children.In this randomized clinical trial 66 children aged 5 to 15 years who underwent elective adenotonsillectomy were randomly allocated into two groups. Patients in the control group received 5 ml of normal saline while patients in the ketamine group received 0.25 mg/kg of ketamine in 5 ml volume during induction of anesthesia. After termination of surgeries and transferring the patients to recovery, emergence agitation, pain score, paracetamol requirements and incidence of postoperative nausea & vomiting were assessed every hour for 6 hours.Emergence agitation score was significantly lower in the ketamine group (P = 0.002). Pain score at all hours was lower in the ketamine group than the control group (P < 0.05). The requirements for intravenous paracetamol were significantly lower in the ketamine group (P = 0.0036). There was no difference in the incidence of postoperative nausea and vomiting between the two groups (P = 0.99).Low-dose ketamine during induction of anesthesia improves emergence agitation and postoperative pain following adenotonsillectomy in children.