Introduction. New methods for studying brain functions have provided the new insights into human brain. It is really possible to study a cortical adaptation in adults who have sustained injury. We reported cortical changes in a left frontal low-grade glioma patient during disease progression and after reoperation by functional magnetic resonance imaging (fMRI). Case report. The use of fMRI exams for localisation of eloquent motor and language areas were performed three times in a period of 15 months: seven years after initial tumor resection, eleven months later and three months after the reoperation. The first fMRI demonstrated cortical activation for motor tasks in the expected location of primary motor area while later examinations showed activations of both primary motor areas for right hand movement. The first exam language evaluation showed the left hemisphere dominance for both language tasks, while the second fMRI demonstrated the right hemisphere dominance for complex word generation task, but the left hemisphere remained dominant in simple language task. After the reoperation, language mapping revealed the left hemisphere dominance for both language tasks. Conclusion. fMRI evaluation of cortical changes in low-grade glioma patients may additionally optimize and individualize neurosurgical treatment.