We performed 148 open magnetic resonance imaging (MRI) surgeries at Tokyo Women?s Medical University between March 3, 2000 and December 13, 2002. Especially for malignant brain tumors located in or adjacent to the functional region, we have tried to improve resection rate and to preserve critical brain function by means of not only intraoperative MRI but also concomitant application of various technique including awake surgery, real-time update navigation, chemical navigation, intraoperative soft X-ray irradiation, etc. In our 46 malignant glioma cases an average resection rate achieved 91% as revealed using pre- and post-operative MR images. A total removal rate was 39% compared to 8% of statistics of the Brain Tumor Registry of Japan 1981 to 1992 [6]. Here we describe a newly innovated neurosurgical system with special reference to the augmented reality including information-guided navigation system (High Definition Visual Computer- Aided Surgery System: HivisCAS), and computer-aided design and computer-aided manipulation (CAD-CAM) surgery.