Objective To explore the expression of yes-associated protein 1 (YAP1), as a key protein of Hippo signal pathway, in rats with brain injury. Methods A total of 18 Sprague Dawley rats were randomly divided into three groups: normal group, sham operation group and brain injury group. The expression of YAP1 in rats with brain injury was detected by immunochemistry, quantitative polymerase chainreaction and Western blotting. Result Seventy-two hours after the brain injury, the expression level of YAP1 in protein and gene increased significantly in brain injury group, compared with those in the normal and sham operation group (P<0.05). Conclusion The expression of YAP1 increases in rats with brain injury, which maybe a new target for therapy.