Pulmonary comp1ications following surgery continue to be a major cruse of postoperative mobidity. The purpose of this study was to measure the effects of various surgical procedures upon arterial blood gas tension and ventilatory function in the early postoperative period. 30 patients with no history of cardiopulmonary disease before surgery were selectively chosen and divided into 4 categories depending on the location of the operative incision and the type of anesthesia. Group l was composed of upper abdominal incision cases, Group ll lower abdominal incision cases, and Groups lll and lV had nonabdominal surgery. Groups, l, ll and lll received general anesthesia, while lV was liven spinal anesthesia. Lung volumes were measured and blood samples were taken preoperatively and 70 minutes after surgery. Patients were maintained in semisitting position before and after surgery. Vital capacities were significantly reduced in the postoperative period in the general ane- sthesia groups, and tidal volumes were significantly reduced in the upper and lower abdominal incision groups. The mean PaO2 value after anesthesia decreased significantly in the upper and lower abdominal incision groups, but there were no significant differencea in the PaCO2 value. It seems that supplemental oxygen and encouragement of deep inspirations are essential and beneficial in the early postoperative period, especially for the patients with abdominal surgery.