Several reports have suggested the importance of p73 polymorphisms in tumor behavior. We investigated the role of a p73 gene polymorphism in the susceptibility to cervical lesions in a southwestern European population. Peripheral blood samples were obtained from Radiotherapy and Gynaecology Departments of Portuguese Institute of Oncology (Porto, Portugal), from 1998 to 2002. We analyzed the p73 cytosine thymine polymorphism in peripheral blood DNA of 176 healthy donors, 38 high-grade squamous intraepithelial lesions (HSIL), and 141 patients with primary untreated invasive cervical cancers (ICC), by polymerase chain reaction-restriction fragment length polymorphism. Our results demonstrate a twofold increased susceptibility to the development of HSIL in women carrying the p73 AT allele (OR=2.39; p=0.022). Further, this association seems to be more evident in women with high parity (OR=12.53; p=0.007). This is in agreement with the possible role of p73 in cervical carcinogenesis, namely, in human papillomavirus-infected transition zone subjected to the action of estrogens and in conjunction with disruption of differentiation program of this squamous epithelium that occurs in HSIL phase before the next step to invasiveness and squamous cervical cancer.