Magnetoencephalography (MEG) is a noninvasive option for localizing electroneurophysiological activity on the human cortex. The purpose of this study was to evaluate the practicability and reliability of MEG imaging integrated into a neuronavigation system to identify the sensorimotor cortex intraoperatively in patients with brain tumors in or near the central motor strip. It was performed prior to surgery in 30 patients with space-occupying lesions in or around the central region to localize the primary somatosensory cortex. These functional brain maps were superimposed on MR images obtained prior to surgery and transferred in the operating room for intraoperative functional neuronavigation. During surgery, the phase reversal technique identified a generator which coincided with the somatosensory cortex as displayed by the MEG-based functional neuronavigation system. Following surgery, the motor deficit improved in seven patients, was unchanged in five, and showed a slight transient deterioration in five. One patient suffered a deterioration of motor function with incomplete recovery. The MEG-based functional neuronavigation was found to be practicable and useful in finding a safe approach to tumors in or adjacent to the central region. The accuracy of MEG was concluded to be reliable as verified by the phase reversal technique.