BACKGROUND: Many pieces of previous research on measuring blood pressure (BP) using different methods focused on the disparity in the results. However, none of them dealt with the disparity caused by the difference in age and inhalation anesthetics. We attempted to find the variance in accordance with age, body part, and measuring methods (invasive vs noninvasive) and also studied how sevoflurane influences BP as the operation progresses. METHODS: In sixty patients, we measured the arterial BP in the upper and lower limbs by noninvasive methods before inducing anesthesia. After induction, we used sevoflurane to maintain anesthesia, and injected catheters into the radial artery and dorsalis pedis artery to measure arterial pressure at every ten minute by both invasive and noninvasive methods. RESULTS: The patients who were 40 or older showed significantly higher values in the systolic BP than the patients younger than 40. The values of systolic and diastolic BP measured by a noninvasive oscillometric method were meaningfully higher than those measured by an invasive method. As the operations progressed, the lower limbs showed higher systolic pressure than the upper limbs regardless of measuring methods, whereas the opposite is true for diastolic pressure. CONCLUSIONS: The values in the arterial BP were measured high by noninvasive method. Systolic BP were estimated significantly high in the older patients and in the lower leg. Due to the effect of sevoflurane, the diastolic BP in the lower limbs becomes lower than that of upper limbs regardless of measuring methods, as the operation progresses.