Objective: To evaluate the reliability of a series of non-invasive methods in the presurgical lateralization of mesial temporal lobe epilepsy (MTLE). Methods: The results of the interictal scalp electroencephalogram (EEG) and ictal scalp EEG, clinical seizure symptom, MRI and interictal SPECT obtained from 40 patients with MTLE who had been followed up 1 to 4 years without seizure after anterior temporal lobectomy (ATL) retrospectively were analyzed in Xuanwu Hospital from May 2002 to May 2005.Results: (1) Unilateral anterior temporal spikes were found on interictal EEG in 37 (92.5%) patients, of whom 35 (94.6%) were in accordance with the lateralization of epileptogenic focus. (2) Ictal scalp EEGs were recorded in 32 patients, from which epileptogenic foci were lateralized in 26 of the 32 patients (81.2%), the concordant rate being 96.2%. (3) Twenty-three patients (57.5%) had clinical seizure symptoms referring to lateralization, of whom 19 (82.6%) had symptoms identical to the lateralization of epileptogenic focus. (4) Thirty-eight patients (95.0%) showed structural abnormalities of unilateral hippocampus or temporal lobes on MRI which were in accordance with the lateralization of epileptogenic focus in 37 patients. (5) Interictal SPECT was measured in 23 patients, which was identical with the lateralization in 18/22 (81.8%). Conclusions: Among a series of non-invasive methods in the presurgical lateralization of mesial temporal lobe epilepsy, SPECT is the most sensitive one, then sequently comes MRI, ictal scalp EEG, interictal scalp EEG and clinical seizure symptom. MRI is the most reliable one, then comes ictal scalp EEG, interictal scalp EEG, clinical seizure symptom and SPECT in a sequent order.