Background: Epilepsy concerns at least 0.5% of population and in most of the cases (approx. 70%) can be treated pharmacologically, which helps to prevent seizures. In all other patients, such a treatment does not produce the desired results. Their condition may require neurosurgical management. The aim of this work was to fuse anatomical MRI images and functional SPECT images in patients with drugresistant epilepsy, without structural changes on MRI or with changes so severe that it would be impossible to establish which ones are responsible for seizures. The authors presented a case of a child subjected to a neurosurgical procedure carried out on the basis of the fused MRI and SPECT images. Case Report: A seven-year-old boy with an extensive defect of the right hemisphere (cortical dysplasia with multiple balloon-like cells) operated on three times due to a history of treatment-resistant seizures present since the age of one. A subsequent MRI examination was performed with magnetic field intensity of 1.5 T, within a routine epilepsy protocol applying volumetric thin-slice T1-weighted images. Next, in the interictal period, a SPECT examination was performed with the use of the 99mTc-labelled ethyl cysteinate dimer (99mTcECD). For fusion and postprocessing, the following software was used: PMOD (Biomedical Image Quantification PMOD Technologies) with PFUS (Flexible Image Matching and Fusion Tool) and a program for a quantitative analysis of counts in the region of interest, so called VOI Constructor (Volume of Interest Constructor). On the basis of the fusion of images, the boy was subjected to the next operation procedure. The remaining fragments of the right frontal and parietal lobe adjacent to the occipital lobe were removed. Seizure remission was obtained and it was already 31 months long when we were writing this article. Conclusions: Owing to this multi-stage procedure, it was possible to avoid a total anatomical and functional hemispherectomy. This allowed for a resection limited to regions indicated by integrated imaging. Removal of cortical areas including lesions was advantageous in this presented case, as it allowed for saving active regions of the brain.