BACKGROUND: The two problems in treating intracranial aneurysm are the vascular reconstruction and brain protection, especially for complex internal carotid artery-posterior communicating artery (ICA-PComA)aneurysms.OBJECTIVE: To analyze the anatomic features and operative technique of complex ICA-PComA aneurysms, and investigate how to better protect the brain tissue.DESIGN: A retrospective case analysis.SETTING: Department ofNeurosurgery, Dalian Central Hospital.PARTICIPANTS: Totally 154 inpatients with ICA-PComA aneurysms were selected from the Department of Neurosurgery, Dalian Central Hospital from January 1998 to December 2006, including 19 cases (12.3%)of complex ICA-PComA aneurysms, 8 males and 11 females, 38 - 67 years of age. Informed contents for surgery and observation were obtained from all the patients or their relatives.METHODS: The clinical manifestations, including initial symptoms and Hunt&Hess grading, were observed. Corresponding strategies were selected for different types of ICA-PComA aneurysms. The patients were followed up at 3 months postoperatively. According to the results of Glasgow scoring, the curative effects were classified as good (4 - 5 points), bad (2 - 3 points) and dead (1 point). The results at discharge were taken as early results, whereas the follow-up results as late results.MAIN OUTCOME MEASURES: Clinical manifestations and curative effects of the patients.RESULTS: All the 19 patients with ICA-PComA were involved in the analysis of results. For clinical manifestations, the initial symptoms were subarachnoid hemorrhage (n =15), paralysis of oculomotor nerve (n =3), and occasional attack (n =1); The Hunt&Hess grading was grade Ⅰ in 4 cases, grade Ⅱ in 6 cases,grade Ⅲ in 6 cases, grade Ⅳ in 2 cases, and grade Ⅴ in 1 case. The curative effects were that aneurysm breakage and bleeding occurred in 6 cases perioperatively, uncomplete clipping of aneurysm in 2 cases and constriction of parent artery in 1 case. The complications were nervous and ischemic ones. The early outcome was good in 12 cases and bad in 7 cases, no one died. The late outcome was good in 17 cases and bad in 2 cases.CONCLUSION: Complex ICA-PComA aneurysm is a particular aneurysm, thus different operative strategies should be adopted according to the conditions to improve the operative outcome and reduce ischemic and nervous injuries.