OBJECTIVE: To investigate the effect of microcatheter shaping based on the parent artery mainstream line of blood flow simulated using the computational fluid dynamics (CFD) technique on embolization of unruptured aneurysms on the posterior wall of the anterior cerebral artery (ACA) A1 segment. METHODS: Patients with unruptured cerebral aneurysms on the posterior wall of the ACA A1 segment were retrospectively enrolled and treated with endovascular embolization after microcatheter shaping. The clinical, embolization, and follow-up data were analyzed. RESULTS: Eight patients were enrolled and treated with endovascular embolization. 8 microcatheters were steam-shaped in vitro and were all successfully navigated to the right location in the in vitro experiment. During the embolization procedure, 7 microcatheters were successfully navigated to the right location for embolization. In the remaining 1 patient who had tortuous cerebral arteries, reshaping of the microcatheter based on the parent artery mainstream of blood flow made successful navigation of the microcatheter to the right place. Complete occlusion was obtained in 7 (87.5%) aneurysms and residual aneurysm neck in the remaining 1 (12.5%). At angiographic follow-up in 6 (75%) patients, the Raymond grade was I in 5 (83.3%) and II in the rest 1 (16.7%). CONCLUSIONS: Use of computational fluid dynamics simulation of parent artery blood flow for microcatheter shaping in the embolization of unruptured aneurysms on the posterior wall of the ACA A1 segment is safe and effective in navigating the microcatheter to the right location for embolization, resulting in good stability and support for the embolization.