Purpose: To achieve maximal safe resection during brain tumor surgery, functional image-merged neuronavigation is widely used. We retrospectively reviewed our casesin which diffusion tensor image (DTI)-merged functional neuronavigation was performed during surgery. Materials and Methods: Between November 2008 and May 2010, 123 patients underwent surgery utilizing DTI-merged neuronavigation. Anatomical magnetic resonance images (MRI) were obtained preoperatively and fused with DTI of major white matter tracts, such as the corticospinal tract, optic radiation,or arcuate fasciculus. We used this fused image for functional neuronavigationduring brain tumor surgery of eloquent areas. We checked the DTI images togetherwith postoperative MRI images and evaluated the integrity of white matter tracts. Results: A single white matter tract was inspected in 78 patients, and two or more white matter tracts were checked in 45 patients. Among the 123 patients, a grossly total resection was achieved in 90 patients (73.2%), subtotal resection in 29 patients (23.6%), and partial resection in 4 patients (3.3%). Postoperative neurologic outcomes, compared with preoperative function, included the following: 100 patients(81.3%) displayed improvement of neurologic symptoms or no change, 7 patients(5.7%) experienced postoperative permanent neurologic deterioration (additionalor aggravated neurologic symptoms), and 16 patients (13.0%) demonstrated transient worsening. Conclusion: DTI-merged functional neuronavigation could be a useful tool in brain tumor surgery for maximal safe resection. However, there are still limitations, including white matter tract shift, during surgery and in DTI itself. Further studies should be conducted to overcome these limitations.