To carry out a comparative study between metoclopramide and dexamethasone to find out its effect by the way of preoperative administration on the rate of postoperative emesis in children who undergoing tonsillectomy. Patients and Methods: Ninety patients between the age of 3-14 years who planned for tonsillectomy were enrolled in our study. Patients were randomly divided into three main groups: Group I: In which children received Dexamethasone injection with a dose of 0.15 mg/kg IV (n = 30). Group II: In which children received Metoclopramide injection with a dose of 0.15 mg/kg IV (n = 30). Group III: In which children received 4 ml saline (n = 30). All episodes of Postoperative vomiting were recorded Results: There were no significant differences between these three main groups of patients regarding the age, sex, weight, type of surgery, duration of surgery and duration of anesthesia. The incidence of vomiting throughout the initial four hours (0-4 hours) was not wasn't considerably different between the three groups, three patients (10%) in the dexamethasone group compared with 3 patients (10%) in the metoclopramide group and 4 patients (13%) in the saline group (P < 0.05). The incidence of vomiting during (4-24 hours) was more frequent in the saline group, 8 patients (27%) developed vomiting (P < 0.001). Only three (10%) patients in the metoclopramide group vomited during this period compared with 6 patients (20%) in the dexamethasone group Conclusion: Metoclopramide found to be more effective than dexamethasone in preventing vomiting in children undergoing tonsillectomy.