The aim of study was, comparison of effects of Metoclopramide and Dropridol associated with Dexamethasone on prevalence of nausea and vomiting after operation was considered. In this study 160 patients ASA physical status I were divided into two groups. In both groups, premedication and induction of anesthesia were given equally according to weight. To the first group, Metoclopramide associated with Dexamethasone and to the second group, Dropridol associated with Dexamethasone was ordered. At the end of the operation, after removing tracheal tube, prevalence of nausea and vomiting in both groups was considered after 2 h and results were analyzed with t-test and Chi-square. Ratio of nausea and vomiting after operation in the first group was 24% and in the second 8%. So results show that prevalence of nausea and vomiting in the second group was considerably lower than the first group (p < 0.004). According to the results of this study our conclusion, Dropridol with dexamethasone given at the before of general anesthesia was more effective in decreasing the prevalence of nausea and vomiting in patients compared with metoclopramide with dexamethasone.