Recently, with the remarkable theoretical progress made in anesthesiology these years, reports are being made on the results of the study on the complications, minor or major, caused by previous general anesthesia. However, .the reports on incidence vary according to the reporters. According to Riding, the recent development of anesthesiology, anesthetic inatruments, knowledge of physiology, anesthetics, induction agents and muscle relaxants are said to have reduced the incidence of complications to a great extent. Riding, Gold and Dyrberg report that the factors capable of influencing the incidence of complication, in the post-operative period include age, sex, premedicants for anesthetics, inhalation method of anesthetics, time of anesthesia, muscle relaxant, use of induction agent, acid-base imbalance and developed knowledge of physioloy, operation site, mental state of patients before operation, general condition, anesthetic technique, and. adequate selection of medicine. Working for Department of Anesthesiology, Hanyang University, from October 1976 to August 1977, we selected, out of the patients who received general anesthesia, 523 males and 372 females, totalling 895, who showed no abnormal symptoms in their respiratory systems, circulatory systems and metabolic systems and observed the incidence of complication in the light of sex, age and operation site, the factors supposed to affect the incidence. An hour prior to the general anesthesia, the patients were given intramuscular injection with premedicants atropine 0. 01 mg per kg, Valium 0. 2 mg or Demerol 1 mg per kg of body weight. For induction of anesthesia, Epontol 10 mg per kg and succinylcholine 1 mg per kg of body weight were injected in the veins, then ventilation was made for a minute with mask and then endotracheal tubes were inserted. and then a minimum amount of air was injected. into the cuff of the endotracheal tube, and the ventilation was done in a semi-closed system. During the period of maintenance, anesthesia was administered in a semi-closed system with 0. 5~l. 0% halothane, 3 L/min of nitrous oxide, 2 L/min of oxygen; and if need be, muscle relaxant was injected into the vein. In case a nondenolarizing agent was used in the course of maintenance, atropine 0. 5~1. 0 mg and neostigmine 2.0 ~ 4.0 mg were injected into the vein for reversion at the recovery time. After the patient was completely recovered, the endotracheal tube was cautiously removed, so as not to give trauma to the throat. As for method of observations, 24 hours after the patient had recovered, we visited the patient in the ward, first observing the existence or nonexistence of incidence of minor complications, and then calculating the incidence by the distribution of sex, age and operation site. The outcome of the observation of the above results by statistics and by chi square test is as follows; 1) the incidence of complications after general anesthesia was high in females. 2) Age has not affected the incidence of complications. 3) The incidence of nausea was highest in the patients with abdominal operation. 4) The incidence of sore throat was highest in the head and neck patients. 5) The incidence of fever was highest in the abdomen patients. 6) The incidence of headache was highest in the head and neck patients.