Genital human papillomavirus (HPV) infection is causally linked to cervical cancer, yet little is known regarding HPV prevalence in cancerous and normal women in Mexico, a country with a high cervical cancer incidence. We studied 185 Mexican women among the patients attending gynecological outpatient clinics in four hospitals in Mexico City. Each woman had a Pap smear, a colposcopy, and, when necessary, a biopsy. HPVs were identified by a consensus-primer-based polymerase chain reaction (PCR) assay. HPV was detected in 87% of 69 cancers, 83% of 24 high-grade squamous intraepithelial lesions (HGSILs), 33% of 21 low-grade squamous intraepithelial lesions (LGSILs), and 17% of 71 normals. Twenty-one of the 32 HPV types tested were detected at least once. The ratio of high-risk:low-risk types was 87:6 in HGSILs and cancers, compared to 11:8 for LGSILs and normals. In invasive cancers, HPV types found at the highest frequency were, in descending order: HPV-16, -18, and -45, followed by -39, -59, and -58 with the same frequency. HPV-16 and related types were present in 52% of the cancer cases, as well as in 79% of HGSILs, and HPV-18 and related types were present in 36% of the cancers but in only 12.5% of the HGSILs. HPV-16 was predominant in squamous carcinomas, and HPV-18 and related types were predominant in adenosquamous carcinoma. Both biopsies and scrapes were tested for HPVs in 63 women, all of them with cervical neoplasia. Identical HPV results were obtained in 89% of the samples, but additional types were often identified in scrapes. HPV prevalence and type distribution in cervical cancer in Mexico was similar to the reported worldwide, as well as in other Latin American countries.