AIM:To investigate the expression of IL-17 in herpes stromal keratitis(HSK).METHODS:HSK models were established with inoculating herpes simplex virus type 1(HSV-1) KOS strain at 1.0×106 plague forming unit to corneas of 35 BALB/c mice.The another 5 normal BALB/c mice served as the control group.Immunohistochemistry was performed using polyclonal antibodies to detect the expression of IL-17 in corneal sections.By flow cytometry,the expression of IL-17 surface protein on CD4+ T cells in murine peripheral blood was evaluated on the 1-3 days,7,10,14,21,28 days after corneal inoculation with HSV-1.Corneal changes were observed under slit-lamp microscope to examine the histopathological changes of corneas.RESULTS:The expression of IL-17 was visible on HSK mice corneal fibroblasts,epicytes and inflammatory cells.Absent staining for IL-17 was seen in the normal sample and negative control sample.The expression of IL-17 in the lymphocytes were harvested from the peripheral blood by flow cytometric analysis.On HSK mice inflammatory cells in stroma significantly increased and the degree of corneal opacity became significantly severe.The intensity of IL-17 expression was significantly positively correlated with the inflammation of HSK(r=0.609,P<0.01).CONCLUSION:IL-17 is overexpressed in corneal and peripheral blood of HSK mice,indicating that IL-17 may contribute to the inflammatory responses of the eye in HSK.