Objective To investigate the expression of Wnt3a and β-catenin in the cortex and the hippocampus after traumatic brain injury in mice and its clinical significance.Methods A mouse model of traumatic brain injury was established,and Western blotting and immunohistochemistry were used to measure the changes in the protein expression of Wnt3a and β-catenin after traumatic brain injury.Results The control group had low expression of Wnt3a and β-catenin in brain tissue.At 1 hour after traumatic brain injury,the content of β-catenin and Wnt3a in the cortex and the hippocampus started to increase.At 6 hours and 7 days after traumatic brain injury,the traumatic group had significant increases in the protein expression of β-catenin and Wnt3a (P<0.05).Immunofluorescent staining showed that at 24 hours after brain injury,there were increases in the expression of β-catenin and Wnt3a in the cortex and the hippocampus.Conclusions The protein expression of Wnt3a and β-catenin increases significantly in the early stage and recovery stage after traumatic brain injury,suggesting that Wnt3a and β-catenin may play important roles in the pathophysiological mechanism of traumatic brain injury.