Objective To explore the applied effects of microsurgical treatment on mesial temporal lobe epilepsy (MTLE) under the guidance of the intraoperative magnetic resonance imaging neuronavigation system.Methods The anterolateral temporal lobe,hippocampus and amygdala was resected by microsurgery under the guidance of the intraoperative magnetic resonance imaging neuronavigation system in 26 patients with intractable MTLE,with the help of electrocorticography monitoring during operation.Results Anterolateral temporal lobes were all resected in postoperative MRI and mesial structures certified to have atrophy or cirrhosis by pathology.All the patients were followed up from 3 to 6 months after the surgery.In 26 patients,twenty-three cases (88.5％) belonged in Engel grade I,two cases (7.7％) in grade Ⅱ and 1 case (3.8％) in gradeⅢ.No severe complications occurred and nervous functions were preserved well.Conclusion Microsurgical treatment on MTLE under the guidance of the intraoperative magnetic resonance imaging neuronavigation system is effective due to epileptic focus all resected and protection for nervous functions,resulting in an accurate and safe improvemention of operation.