There are many reports about post-anesthetic nausea and vomiting. Pst-anesthetic nausea and vomiting can cause not only severe discomfort but also many complications. McKie (1970) said that the incidence varies from 23% 82%. But nowadays, the incidence seems greatly decreased due to the development of anesthetic techniques and anesthetic agents. We studied the incidence and factors affecting nausea and vomiting in 564 patients under general anesthesia from July 1, 1975. to September 30, 1975. at Severance Hospital, The conclusions are as follows; (1) The over all incidence is 34%. (2) It is more common in women. (3) It is less common below 10 years of age. (4) It is more common after prolonged anesthesia. (5) It is most common with ether. (6) It is more common when parasympatholytic agents are used for premedication. (7) It is most common in abdominal operations. We also studied post-anesthetic headache, and the incidence was 15%. Post-anesthetic headache was most common with halothane. There are many different opinions about the effect of the prophylactic use of antiemetics for post-anesthetic nausea and vomiting. So we studied the prophylactic antiemetic effect in ether anesthesia with the use of perphenazine HCI (Trimin). The antiemetic reduced the incidence from 42% to 3% in cases using ether.