Five cases of cerebral arteriovenous malformation(AVM) are presented, which underwent total extirpation using the operating microscope. The following are considerations which favor the total extirpation of AVM and the advantages of using the operating microscope, including the rationale for non-use of hypotensive anesthesia or mannitolization which is commonly used in intracranial aneurysm surgery: 1) Relatively small sized AVMs are found to show a high rate of large intracerebral hematoma, including that the degree of bleeding from the malformed vessels is not related to the size of the AVM. 2) The operating microscope facilitates the following procedures: a) determination of the extent of the malformed vessels. b) clipping feeders. c) identification of red vein and laminar flow. d) preservation of normal brain tissue.