PURPOSE: Mesio-temporal ictal semiology is sometimes observed in patients with large multilobar lesion. In this situation, surgery is often discarded because of the lesion size and/or suspicion of extended or multifocal epileptogenic areas. In this retrospective study we evaluated the surgical outcome of such patients in order to assess whether the electro-clinical presentation of seizures could be a prognostic marker of surgical outcome. METHODS: Among the temporal lobe epilepsy population explored in our department between 2000 and 2011 (240 patients), we identified 7 patients who presented an extensive lesion on brain Magnetic Resonance Imaging (MRI) (multilobar in four, hemispheric in two, and bilateral in one). All patients underwent (18)Fluorodeoxyglucose Positron Emission Tomography, which showed large, hemispheric or multilobar, areas of glucose hypometabolism. Because of the large lesion size, all patients were explored by stereoelectroencephalography (SEEG) before taking a decision regarding surgical indication. RESULTS: SEEG confirmed the temporal origin of the seizures and discarded the possibility of multiple epileptogenic zones. A temporal lobectomy, tailored on the basis of SEEG data, was proposed to the seven patients. The seven patients are classified Engel class I after the surgery (mean follow-up: 37.4+/-22.1 months). CONCLUSION: Our data thus suggest that, even in the absence of hippocampal MRI abnormality, ictal symptoms compatible with a temporal origin of seizures should be considered as a reliable indicator for surgery eligibility regardless of MRI lesion size. On the basis of our findings, the mesio-temporal semiology of seizures appears as one of the most reliable markers of operability in patients with large MRI lesions. These patients should not be excluded a priori from invasive exploration and surgical treatment, even if a large portion of their lesion is likely to be left in place after surgery.