Immunohistochemical method was used to examine the immunoexpression of PD-L1 and number of Foxp3+, CD4+, CD8+ cells in 78 cases of oral squamous cell carcinomas (OSCCs): with better prognosis - OSCCBP (n = 37), and with poorer prognosis - OSCCPP (n = 41), and 18 cases of normal mucosa as a control. The gene discussed is CD4; the disease is oral cavity squamous cell carcinoma.