The positive rate of NQO1 protein expression was only 12.00% (3/25) in non-neoplastic cervical tissues, but significantly higher in CIN lesions (41.38% in CIN-1, 52.63% in CIN-2 and 55.56% in CIN-3) and SCCs (80.23%, 142/177) of the cervix (P < 0.01). Here, NQO1 is linked to cervical squamous intraepithelial neoplasia.