The aim of this study was to determine whether the codon 31 genotype of p21 might be associated with an increased risk of cervical cancer development in Korean women. We used tissue derived from patients with invasive cervical cancer (ICC) (n=111, composed of two histologic groups: squamous cell carcinoma (n=67) and adenocarcinoma (n=44)), cervical intraepithelial neoplasia (CIN) III (n=101), and non-cancer controls (NCC, n=98). For the determination of p21 polymorphism, genomic DNA was examined by polymerase chain reaction-restriction fragment length polymorphism assay using BsmAI. We compared the distribution of the p21 genotype in ICC, CIN III, and control and also analyzed the association of this polymorphism with the risk of development of cervical cancer, especially in patients with high-risk human papillomavirus (HPV) (16 or 18)-positive cervical cancer. A significant increase of Ser/Ser genotype frequency was found in adenocarcinoma patients with high-risk HPV (16 or 18) compared with the NCC group (P=0.009). The odds ratio was 3.59 (95% CI 1.55-8.31) when comparing adenocarcinoma patients associated with high-risk HPV with NCC. We found that the codon 31 Ser/Ser homozygote of the p21 gene could be a risk factor for the development of cervical adenocarcinoma associated with high-risk HPV.