Objective To investigate the expression and significance of Cyclin D1 in oral squamous cell carcinoma（OSCC）. Methods A immunohistochemistry method, Envosion, was employed to test the manifesting levels of Cyclin D1 in pathological slices of 50 OSCC cases and 10 normal cases, and the results was treated with statistical analysis. Results In 50 OSCC cases, Cyclin D1 mainly manifested in karyon, and a little in cytoplasm. The positive manifesting rates of Cyclin D1 in the samples was 80.0%, which was significantly higher than the manifesting rates of 20.0% in normal oral mucous membrane（P
