The position of the patient’s head is of enormous importance in the operation under an operating microscope. There are two points to which particular attention must be paid. One is the height of the patient’s head, which should be above the level of the heart in order to lower both venous and intracranial pressure. We make it a rule in the supine and prone positions to elevate the upper half of the operating table by about 30 degrees; raising the head more than 45 degrees runs the risk of air embolism. The second point is that the main operating procedure can and should be performed with the microscope at a constant perpendicular visual axis by rotating and/or tilting the patient’s head. Working under a microscope at an oblique angle for a long period is very tiring. Intraoperative correction of the head position to either side can be easily done by rotating the head frame or tilting the operating table sideways. However, it is difficult to correct the degree of flexion or extension of the head once surgery starts, and it is therefore important to position the head properly in the vertical axis prior to surgery: the chin up or down in the supine position, and the vertex up or down in the lateral position (Figs. I-1 and I-2).