We reviewed the intraoperative monitoring and anesthesia in 45 patients, who had undergone operation of lesions involving the cavernous sinus between September, 1990, and May, 1993. The patient was placed in a 30 degree of head-up position to reduce the bleeding from the cavernous venous plexus. However, air embolism during the operation has not been noted in any patients. In 13 of 45 patients, a transient or permanent internal carotid artery (ICA) occlusion was performed intraoperatively under the brain protection by thiopental and the monitoring of electroencephalograph, somatosensory evoked potentials, local cerebral blood flow, and oxygen saturation of internal jugular vein. There has been no complications related to the ICA occlusion. In 7 patients, intraoperative recordings of evoked extraocular muscle activities were undertaken to monitor ocular motor nerve function. Responses from the inferior rectus muscle to the oculomotor nerve stimulation, and from the lateral rectus muscle to the abducens nerve stimulation, were obtained in 5 patients and 1 patient, respectively. Intraoperative neurophysiological monitoring in the surgery of lesions involving the cavernous sinus is crucial to reduce the surgical complications, and a team approach, including neurosurgeons, anesthesiologists, and medical engineers, is important for the future progress.