Objective     To investigate the expression of human papillomavirus type 16 E6 (HPV16E6) and p53 in human oral cancer and their relationship with clinical stage and histopathological grade. Methods      Expression of HPV16E6 and p53 was detected by immunohistochemical staining in 149 oral cancer specimens

88 precarcinoma tissues and 49 normal oral tissues. Statistical analysis was performed on the positive expression of HPV16E6 and p53 with different clinical stages and histopathological grades. Results     The positive rates of HPV16E6 were 79.9% (119/149) in oral cancer tissues

38.6% (34/88) in precarcinoma tissues and 2.0% (1/49) in normal oral tissues

respectively. The positive rates of p53 were 24.2% (36/149) in oral cancer tissues

55.7% (49/88) in precarcinoma tissues and 91.8% (45/49) in normal tissues

respectively. In parallel with the increases of clinical stage and histopathological grade

the positive rates of HPV16E6 were gradually increased

whereas those of p53 were gradually decreased (P0.05). Conclusion      Up-regulation of HPV16E6 and down-regulation of p53 may contribute to the genesis of human oral cancer. Detection of HPV16E6 and p53 expression may be useful to evaluate the malignancy of oral cancer.