BACKGROUND In this study we investigated the effect of urinary kallidinogenase (UK) on transforming growth factor beta 1 (TGF-β1) expression in brain tissue. We also explored the neuroprotective mechanism of UK against ischemic injury by measuring serum high-sensitivity C-reactive protein (hs-CRP) level changes after rat cerebral ischemic injury. MATERIAL AND METHODS The rat middle cerebral artery ischemia/reperfusion model was established using the suture method. Sprague-Dawley rats were randomly divided into 3 groups: treatment, Gegen control, and blank control. Each group was subsequently divided into 5 subgroups according to time (6, 12, 24, 48, and 72 h). Rats in the treatment group were administered UK as treatment. TGF-β1 expression was observed at each time point using SABC and immunohistochemical staining methods to estimate cerebral infarct volume percentage. Serum hs-CRP levels were also measured. RESULTS TGF-β1 protein expression in ischemic brain tissues of the treatment group significantly increased at each time point (P<0.01) compared with both control groups. Treatment group serum hs-CRP levels significantly decreased at each time point (P<0.05) compared with both control groups. CONCLUSIONS UK exerts a neuroprotective effect by upregulating TGF-β1 expression and inhibiting excessive inflammatory responses.