PURPOSE: To determine the usefulness of the functional MRI (fMRI) using motor and sensory stimuli in patients with brain tumors or focal cerebral lesions. MATERIALS AND METHODS: This study involved five patients with brain tumors (n=2) or cerebral lesions [cysticercosis (n=1), arteriovenous malformation (n=1), focal infarction (n=1)] and seven normal controls. For MR examinations a 1.5T scanner was used, and during motor or sensory stimulation, the EPI BOLD technique was employed. For image postprocessing an SPM program was utilized. RESULTS: In volunteers, contralateral sensori-motor cortices were activated by both motor and sensory stimuli, while supplementary motor cortices were activated by motor stimuli and other sensory cortices by sensory stimuli. Preoperative evaluation of the relationship between lesions and important sensory and motor areas was possible, and subsequent surgery was thus successful, involving no severe complications. Activation of ipsilateral or other areas occurred in patients with destruction of a major sensory and/or motor area, suggesting compensatory reorganization. CONCLUSION: fMRI could be a useful supportive method for determining the best approach to surgery treatment in patients with brain tumors or focal cerebral lesions.