Thiopental 6.7mg/kg and ketamine 0.9mg/kg was given for induction of general anesthesia and effect of the drugs on the bioparameters such as the time required for loss of consciousness, the occurance of arrhythmias, the amount of bronchial secretion, changes in blood pressure and pulse rate, and the postoperative complications were investigated in this study. The results were as follows. 1) The time required for loss of consciousness was 28 seconds in the ketamine group and 32 seconds in the thiopental group. 2) The occurance of arrhythmias was less in ketamine group than in thiopental group. 3) The degree of bronchial secretion was similar in both groups. 4) Ketamine did not increase the pulse rate greater anymore thiopental. 5) Blood pressure was significantly lowered after 10 minutes in the thiopental group but not changed in the ketamine group. 6) There was no hallucination or delirium in the two groups.