Infarction, and Hydrocephalus [HCP] . The activeparticipation of macrophage/monocyte-mediated inflammatory response in thepathogenesis of cerebral aneurysm as labeled with Monocyte ChemoattractantProtein-1 [MCP-1] is suggested Objective: To measure the serum level of MCP-1 in rupturedCAs in different time intervals Methods: We measured the serum levels of MCP-1 inSAH patients who had CAs and compared it with that of MCP-1 in two control groups: including patients with SAH without CAs, and the normal population of blood donors. We also measured the MCP-1 levels in patients with CAs one week afterward toevaluate the effect of treatment. Serum level of MCP-1 was measured by a commercial ELISA assay Conclusion: Ourresults did not show an increasing MCP-1 serum level in patients with aneurysmalSAH. There was a relationship between poor clinical grade and MCP-1 levels inpatients with CAs. MCP-1 may be a local inflammatory marker for cerebral aneurysmswithout systemic manifestation