If good anesthesia is to be provided to the patient undergoing surgery for an expanding intracranial lesion, certain principles should be borne in mind. These principles include: 1. Careful preoperative assessment of the patient 2. Awareness of abnormal intracranial dynamics in the presence of an intracranial mass lesion 3. The importance of a smooth induction of anesthesia 4. Adequate depth of anesthesia and complete muscle paralysis before laryngoscopy and intubation 5. The choice of a maintenance technique that does not increase ICP and allows adequate CPP. Failure to adhere to these principles may lead to sudden increases in intracranial pressure, decreased cerebral perfusion pressure, and regional ischemia. In the closed skull, internal herniation of brain tissue through the tentorial notch or the foramen magnum may occur. External brain herniation, with increased bleeding and rupture of cerebral cortex, may occur after the dura mater has been opened if these anesthetic parameters are not controlled. Neuroanesthesia, therefore, plays an important role in the reduction of morbidity and mortality in the surgery of intracranial lesions of all types, including neoplasms - not only in the operating room, but also in the pre- and postoperative care of the neurosurgical patient.