Dissecting aneurysms of the posterior cerebral artery (PCA) are rare, especially those at the P1 segment. Here, we describe the case of a 57-year-old woman with a subarachnoid hemorrhage (SAH). Computed tomography angiography (CTA) and digital subtraction angiography (DSA) revealed a small (3 mm) dissecting aneurysm with the typical peari-and-string sign at the right P1 segment. Fourteen days after onset, the patient developed aphasia. DSA revealed vasospasm of the right middle cerebral artery, and we performed endovascular treatment by the intra-arterial injection of 1-(5-isoquinolinesulfonyl) homopiperazine. After this treatment, the patient's symptoms recovered immediately. Vertebral angiography revealed enlargement of the dissecting aneurysm (up to 7 mm diameter). We started a loading dose of 300 mg aspirin and 400 mg Clopidogrel after observing growth of the aneurysm. Fifteen days after onset, we performed a stent-assisted coil embolization, and obtained nearly complete obliteration of the aneurysm with preserved patency of the parent artery. Six-month follow-up DSA demonstrated complete occlusion of the aneurysm with good patency of the stented PCA: the patient was at modified Rankin Scale 1. In the treatment of ruptured dissecting aneurysms, parent vessel occlusion (PVO) with aneurysm is common. However. PVO may cause both cerebral infarction of the distal area and perforator occlusion of the occluded vessel. Stent-assisted coil embolization can preserve parent vessel flow and obliterate the aneurysm. Stents offer a therapeutic alternative for PCA dissecting aneurysms, especially when PVO cannot be tolerated.