Objective To investigate the safety and clinical efficacy of magnetic resonance neuronavigation assisted technique in neurosurgical clipping of pericallosal aneurysms. Methods From January 2010 to January 2017,40 consecutive patients with pericallosal aneurysm treated with neurosurgical clipping at the Department of Neurosurgery,the 175th Hospital of PLA were enrolled retrospectively. They were diagnosed by CT angiography (CTA),magnetic resonance angiography (MRA)or digital subtraction angiography (DSA)before operation. According to the different surgical methods,40 patients were divided into either a routine surgical group (n＝18)or a neuronavigation assistance group (n＝22). On the basis of the conventional longitudinal fissure approach,the neuronavigation assistance group was treated with the magnetic resonance neuronavigation technique. The aneurysms and upper drainage vein,design incision and surgical approaches were accurately located. The operation time,surgical complications (edema or infarction after drainage vein injury and secondary bleeding in the operated area)and proportion of good prognosis (the modified Rankin scale [mRS]score ＜3)were compared. Results (1)Under the microscope,40 patients underwent clipping of pericallosal aneurysms via longitudinal fissure approach. Postoperative CTA or DSA confirmed that they were all completed clipped. The operation time of the neuronavigation assistance group were shorter than that of the routine surgical group (2. 5 ± 0. 5 h vs. 3. 5 ± 0. 4 h,t＝1. 254),and the proportion of edema or venous infarction was less than that of the routine surgical group (4. 5%[1／22]vs. 6／18). The difference between the two groups was statistically significant (all P＜0. 05);there were no significant differences in the incidences of accidental rupture and secondary hemorrhage between the two groups (all P＞0. 05). (2)Both groups of patients completed the 6-month follow-up. There were 12 patients (12／18)with good prognosis in the routine surgery group and 20 (90. 9%)with good prognosis in the neuronavigation assistance group. There was no significant difference in the proportion of good prognosis between the two groups (χ2＝3. 545,P＞0. 05). Conclusions The use of magnetic resonance neuronavigation assisted technique helps the precise intraoperative positioning of the lesions and surgical approach optimization,thereby effectively implementing brain protection,reducing the risk of microsurgery, and improving the accuracy and safety of the surgery. It is an effective auxiliary means of neurosurgical clipping of pericallosal aneurysms.