Oxyen consumption of surgical patients was measured by McKesson Metabolar (Model 185) on the Recording Metabolar Chart (M-147) in four groups: group A, at resting state immediately before preanesthetic medication; group B, immediately following induction of anesthesia with thiopental (10 mg./kg.); group C. 30 minutes after surgical ether anesthesia; and group D, when conciousness returned during the stay in the recovery room. The results are as follows: (1) Thiopental reduced oxygen consumtion by 25 per cent. (2) Ether anesthesia reduced, oxygen consumption by 59 per cent. (3) During recovery from anesthesia, oxygen consumption was 28 per cent below the control. (4) Comparing with other data, ether anesthesia reduced oxygen consumption significantly more than fluothane or nitrous oxide did.