Human papillomavirus (HPV) plays a major role in the etiology of cervical cancer. However, a complex correlation between viral and cellular genes is necessary for cell cycle control deregulation in the progression to invasive cervical cancer (ICC). Cyclin D1 (CCND1) is an important positive regulator of the G1/S phase of the cell cycle. The CCND1 gene is located at 11q13 and is often altered in human cancers. We analyzed the A870G CCND1 polymorphism by polymerase chain reaction/restriction fragment length polymorphism analysis in 246 women including 50 cases with high-grade squamous intraepithelial lesions of the cervix (HSIL), 93 with ICC, and 103 healthy women. The GG genotype was associated with a 4.32-fold higher risk for the development of HSIL [adjusted odds ratio (aOR)=4.32, 95% confidence interval (CI) 1.50-12.46, P=0.0067), and a 3.26-fold increased risk for the development of ICC (aOR=3.26, 95% CI 1.42-7.53, P=0.006). The proportion of cervical cancer cases attributable to the GG CCND1 genotype was 17.26%. This study indicates that the A870G CCND1 polymorphism could act as a cofactor of HPV in the initiation of cervical carcinogenesis, particularly in the transformation zone of HPV-infected women, supporting evidence for a genetic factor in ICC risk.