Carcinomas of the uterine cervix still constitutes the first cause of death from cancer among Mexican women. Certain types of human papillomaviruses (HPV) have been implicated in cervical cancer development; active viral sequences are usually found in more than 90% of cervical tumors, their genome contains two oncogenes that immortalize human cells in culture. Recent worldwide studies have shown the existence of molecular variants of known HPV types, mainly 16 and 18, thus permitting the establishment of viral spread during evolution, which seems as ancient as humankind. Phylogenetic studies have identified five major branches for HPV-16 and indicated that viral diversity seems associated with ethnic characteristics of the populations. In this work we searched for the presence of viral sequences among cervical tumors from the Mexican population. The existence of variants of HPV types 16, 18, and 45 was observed. One variant was found in more than half of HPV-16 positive tumors, and seems to exhibit a more aggressive behavior. In HPV-18 positive tumors, in addition to the prototype, two variants were detected in near a fourth of the samples. Finally, all HPV-45 positive tumors showed a new variant not yet reported in the literature. Some of these variants were found associated with specific histological types of cervical cancer, suggesting the participation of these variants in its genesis or aggressivity.