OBJECTIVE: Vasospasm is known to play the key role in determining the prognosis of aneurysmal subarachnoid hemorrhage (SAH). We have experienced a higher incidence of vasospasm in the cases of SAH caused by rupture of an anterior choroidal artery (AChA) aneurysm than aneurysms of other area. The purpose of this study is to analyze the ischemic complications in patients with a ruptured AChA aneurysm. METHODS: We retrospectively reviewed 13 patients who were treated for ruptured AChA aneurysm from 1994 to 2007 at our hospital. The prognosis and complications were analyzed based on the institution's data, gender, age, the Hunt and Hess grade, the Glasgow coma scale, the Glasgow outcome scale, the symptoms and neurological examinations, the medical treatment, the digital subtraction angiography (DSA), the computed tomography (CT) and the magnetic resonance imaging (MRI). RESULTS: Forty-one (6%) out of 678 SAH patients had ischemic complications. Thirteen cases (2%) were caused by rupture of an anterior choroidal artery (AChA) aneurysm and 3 of these 13 cases (23.1%) had ischemic complications. Two of these 3 cases (15.4%) had neurological abnormality. Twelve out of the 13 AchA aneurysms had the saccular form. CONCLUSION: In cases of SAH from ruptured AchA aneurysm, the probability of ischemic complications was higher than that of general aneurysmal SAH. This seems to be due to the thin AChA and that the vascular territory of AChA is the area where ischemic brain damage can occur even by a mild vasospasm. So, when operating on a AChA aneurysm, maximum effort should be done to preserve the AChA. However, in the exceptional case with multiple AChAs, one AChA can be trapped without a definitive neurological deficit.