To investigate HPV infection and the protein expression of p16INK4A and p53, and to evaluate their potential roles in the pathological diagnosis and grading of cervical CIN, HPV DNA and p16INK4A and p53 expression were examined in a panel of clinical tissues samples (including 40 SMH, 24 cervical condyloma, 120 CIN and 19 cervical cancer) using polymerase chain reaction (PCR) or immunohistochemistry (IHC). The gene discussed is CDKN2A; the disease is cervical squamous intraepithelial neoplasia.