An inflammatory response following aneurysmal SubArachnoid Hemorrhage (aSAH) plays a significant role in the development of cerebral vasospasm. This study analyzes the correlation between the level of InterLeukin-6 (IL-6) in CerebroSpinal Fluid (CSF) after aSAH and the occurrence of cerebral vasospasm. We analyzed clinical manifestations, laboratory data, and instrumental examination methods in 45 patients who were treated for intracranial aSAH within 21 days, studying the relationship between the development of cerebral angiospasm and the concentration of the inflammatory factor. We found the potential significance of IL-6 in predicting vasospasm, confirmed by cerebral angiography. As a control, we analyzed the CSF samples of 15 patients treated for unruptured cerebral aneurysms. According to the study results, vasospasm developed in 44% of patients, on average on the 6th day from the onset of the disease. Patients with aSAH demonstrated statistically significant (p<0.05) higher mean IL-6 values in CSF on the 3rd, 7th, and 10th days compared to the control group. Patients with vasospasm showed statistically significant (p<0.05) higher mean IL-6 values in CSF on the 3rd day, while the differences on the 7th and 10th days (p<0.05) were not statistically significant. The threshold value for predicting the formation of cerebral vasospasm was determined to be 325 pg/ml on the 3rd day from the onset of the disease. We concluded that IL-6 in cerebrospinal fluid is a potential early marker for predicting vascular spasm after subarachnoid hemorrhage on the 3rd day of the disease, before the onset of clinical manifestations. We concluded that monitoring the value of IL-6 in the cerebrospinal fluid on the third day after aneurysm rupture is potentially significant for the early diagnosis of vasospasm. Keywords: intracranial aneurysm, vasospasm, stroke, cytokines.