Introduction: Subarachnoid hemorrhage is a common neurological disorder that can have added complications such as systemic inflammatory response syndrome has been associated with symptomatic cerebral vasospasm, however the behavior of it and how it relates to other complications is unknown. Objective: To assess by neutrophil / lymphocyte ratio behavior that keeps the systemic inflammatory response in patients with aneurysmal subarachnoid hemorrhage origin. Methodology: 17 patients were evaluated for 15 days from admission to the National Institute of Neurology and Neurosurgery "Manuel Velasco Suarez" in order to describe the behavior that keeps the systemic inflammatory response throughout its evolution and the relationship with the appearance of associated complications such as vasospasm, hydrocephalus, and electrolyte abnormalities. Results: 17 patients of whom 76% had electrolyte disturbances were analyzed; 47% vasospasm and hydrocephalus in 35%. In relation to vasospasm, 30% culminated in areas of infarction and increased value to 10 of the neutrophil / lymphocyte ratio to income directly correlated with the occurrence of vasospasm (p <0.001). Conclusion: The behavior of the systemic inflammatory response in patients with aneurysmal subarachnoid hemorrhage origin is different in those who develop vasospasm, for which there is a direct relationship between (greater than 10) high values of the neutrophil / lymphocyte ratio with the appearance of symptomatic cerebral vasospasm and hydrocephalus.