Basilar artery trunk aneurysms (BATAs) are rare, and among the treatments for all aneurysms, the surgical treatment of BATAs is the most difficult. Endovascular treatment (EVT) of BATAs is comparatively easy; however, EVT of large, wide-necked BATAs remains challenging. Here, we describe a multiple microcatheter technique for detachable coil treatment combined with the use of a stent in 2 patients with large (>20 mm), wide-necked BATAs. 【Case 1】 A 30-year-old man presented with difficulty in swallowing. Angiography showed a large, wide-necked basilar trunk aneurysm. Three microcatheters were positioned in different parts of the sac through each side of the vertebral artery, and a stent was positioned across the aneurysm neck. The aneurysm was occluded with coils placed via the 3 microcatheters. 【Case 2】 A 63-year-old man presented with sudden-onset severe headache and consciousness disturbance. Computed tomography (CT) revealed subarachnoid hemorrhage, and angiography showed a large aneurysm in the lower basilar artery fenestration. One microcatheter each was positioned in the upper and lower part of the aneurysm, and a stent was deployed in the left limb, where a larger part of the aneurysm neck was thought to be present. The aneurysm was then embolized with coils. For the treatment of large, wide-necked aneurysms, stent-assisted coil embolization is useful to avoid coil herniation. However, because the mobility of the microcatheter is often restricted, deviated or unbalanced coiling occurs. Because BATAs can be accessed from both the sides of the vertebral artery, multiple microcatheters can be used to pack the aneurysms uniformly and tightly.