ObjectiveToinvestigatetheroleofimmuneinflammatoryreactionintheformationof intracranial aneurysm. Methods The intracranial aneurysms in 40 patients of craniotomy ( intracranial aneurysm group) and the vascular specimens in 20 craniotomy patients w ith traumatic brain injury (control group) w ere col ected. Fluorescence quantitative polymerase chain reaction w as used to detect the expression of interleukin (IL)-17 receptor in the arterial w al . Flow cytometry w as used to detect the Th-17 cel s in peripheral blood. Enzyme-linked immunosorbent assay w as used to measure the levels of IL-17, IL-6 in the arterial w al and tumor necrosis factor-α( TNF-α) in peripheral blood. Results There w ere no significant differences in the age (62.6 ±8.7 years vs.61.4 ±7.9 years;t=0.342;P=0.681), proportions of male (60.0%vs.65.0%; χ2 =0.246, P=0.434), hypertension ( 12.5%vs.10.0%; χ2 =0.315, P=0.492), diabetes (75.0%vs.10.0%; χ2 =0.284, P=0.482), and smoking (35.5%vs.30.0%; χ2 =0.224, P=0.413) betw een the intracranial aneurysms group and the control group. The expression of IL -17 receptor in the arterial w al (0.106 ±0.032 vs.0.264 ±0.071; t=5.115, P=0.001) and the proportion of Th17 cels in peripheral blood (2.75%±0.53%vs.7.18%±1.54%; t=8.436, P<0.001) and IL-17 level ( 7.32 ±1.82 μg/L vs.22.64 ±4.51 μg/L; t= 8.357, P< 0.001 ) in the control group w ere significantly low er than those in the intracranial aneurysm group. The levels of IL-6 (1.15 ±0.24 μg/L vs. 19.64 ±4.16 μg/L; t=9.527, P<0.001) and TNF-α(1.43 ±0.31 μg/L vs.26.17 ±4.32 μg/L; t=9.816, P<0.001) in the arterial wal in the control group were significantly lower than those in the intracranial aneurysm group. Conclusions The expression of IL-17 receptor in the arterial w al , the proportion of the Th17 cels and IL-17 level in peripheral blood were increased in patients with intracranial aneurysms. Immune inflammation may be involved in the formation of intracranial aneurysm.