Subdural strip electrodes or intracerebral electrodes are used to localise epileptic foci, which is imperative in epilepsy surgery. The precise positioning of the subdural electrodes, which is performed via a bore-hole, is difficult. Therefore their location in relation to the gyri and sulci has to be determined by radiological techniques. In this study, a three-dimensional (3D) MRI technique was used for the localisation of intracranial EEG electrodes in 17 patients suffering from severe epilepsy. A 3D gradient echo sequence with slices of 1 mm thickness was required for the assessment of the gyral anatomy of the brain surface. A short repetition time of 30 ms leads to diagnostic image quality and to an acceptable measurment time of about 15 min. Postprocessing with 3D surface reconstruction was performed using a Sun workstation. Three-dimensional reconstruction allows a more precise registration of the localisation of the EEG elctrodes and the simultaneous display of the adjacent brain structures. The incorrect placement of intracranial electrodes was readily detected in 3 patients. Three-dimensional MRI with 3D surface reconstruction proved superior for the assessment of electrocorticogram electrode localisation compared with two-dimensional imaging and CT.