The forehead sensor of the 5th generation pulseoximeter may provide reliable and stable data, because it measures at supraorbital artery as a branch of internal carotid artery with blood flow autoregulation. We compared the finger sensor (Fig. 1) and the forehead sensor (Fig. 2) of new pulse oximeter in oral surgery under general anesthesia. The subjects consisted of 22 healthy patients who were scheduled for oral surgery under general anesthesia (Table 1). Although general anesthesia methods were not the same, the fixation of each sensor was unified in all cases. Both data from the finger sensor and the forehead sensor of the pulse oximeter (Nellcor N-550, Nellcor Inc. CA) were monitored simultaneously in each patient during general anesthesia, and the data were analyzed and compared. To compare the data between the forehead sensor and the finger sensor, comparison statistical analysis was performed with two-tailed paired t-test, and P<0.05 was considered as significant. In the data of SpO_2 and pulse rate, there were no significant differences between finger sensor and forehead sensor (Fig. 3, 4). However, the amplitude of plethysmograph in the forehead sensor was more stable than the finger sensor (Fig. 5), even if the amplitude of plethysmograph in forehead sensor was significantly lower than finger sensor (p=4.5×10^<-158>). In addition, SpO_2 in the forehead sensor responded sooner than in the finger sensor. However, the artificial fluctuation was developed frequently in the data of SpO_2 of the forehead sensor when the head was moved by operation of oral surgery or dental treatment. The results suggest that the forehead sensor provide a better monitoring site for pulse oximeters, because it measures at supraorbital artery as a branch of internal carotid artery with blood flow autoregulation. More useful physical information about respiration and circulation can be obtained by using both the forehead sensor and finger sensor.