Background and objective Some patients with aneurysmal subarachnoid hemorrhage are found to have intracranial aneurysms with an indication for intervention on the contralateral side to the responsible lesion, and there are still controversies and challenges over the simultaneous treatment of aneurysms in the M1 segment of the contralateral middle cerebral artery. This study was conducted to investigate the feasibility， safety， and efficacy of the simultaneous treatment of responsible lesion and contralateral non-responsible lesion via the frontolateral approach.Methods A total of 8 patients with aneurysmal subarachnoid hemorrhage were admitted to Department of Neurosurgery, Tianjin Medical University, from June 2014 to September 2020, all of whom were treated with simultaneous clipping of the responsible aneurysm and the non-responsible aneurysm in M1 segment of the contralateral middle cerebral artery via the frontolateral approach. The clinical effect of this surgical procedure was evaluated based on the indicators such as Fisher grade, Hunt-Hess grade, location of the responsible aneurysm, distance between the aneurysm in the contralateral middle cerebral artery and the beginning of the ipsilateral M1 segment, orientation and size of the non-responsible aneurysm, modified Rankin Scale (mRS) score at discharge, and Montreal Cognitive Assessment (MoCA) score at discharge.Results There were a total of 18 aneurysms in 8 patients, among which 16 intracranial aneurysms required surgical treatment, and the responsible aneurysm was located in the internal carotid artery (4 patients), the anterior communicating artery (2 patients), or the middle cerebral artery (2 patients). The mean distance was 15.4 mm between the aneurysm in the contralateral middle cerebral artery and the beginning of the ipsilateral M1 segment, and the aneurysms requiring treatment in the contralateral middle cerebral artery had a mean size of 3.4 mm×2.6 mm. Postoperative cerebrovascular CTA showed that the intracranial artery at the distal end of the lesion had a normal shape and smooth vascular walls, without localized stenosis or expansion of the lesion. At discharge, 4 patients had an mRS score of 0, and 4 had an mRS score of 1. MoCA score at discharge suggested that 2 patients had mild cognitive impairment (<26 points) and the remaining patients had normal cognitive function.Conclusions The frontolateral approach has many advantages and is technically feasible in the treatment of contralateral non-responsible aneurysms, which provides new ideas for the treatment of such complex lesions. [Journal of International Neurology and Neurosurgery, 2023, 50(3): 1-5]