The prevalence of HPV infection in Latin America is among the highest in the world. A quadrivalent (types 6/11/16/18) human papillomavirus L1 virus-like-particle vaccine has been shown to be 95-100% effective in preventing HPV 6/11/16/18-related cervical and genital disease in women na€ ıve to vaccine HPV types. A total of 6,004 female subjects aged 9-24 were recruited from Brazil, Mexico, Colombia, Costa Rica, Guatemala and Peru. Subjects were randomized to immunization with intramuscular (deltoid) injections of HPV vaccine or placebo at enrollment (day 1), month 2 and month 6. Among vaccinated subjects in the per-protocol population from Latin America, quadrivalent HPV vaccine was 92.8 and 100% effective in preventing cervical intraepithelial neoplasia and external genital lesions related to vaccine HPV types, respectively. These data support vaccination of adolescents and young adults in the region, which is expected to greatly reduce the burden of cervical and genital cancers, precancers and genital warts. ' 2007 Wiley-Liss, Inc.Key words: HPV; cervical cancer; vaccine Infection with human papillomavirus (HPV) is considered to be an obligate step in the development of cervical cancer. 1 Human papillomavirus DNA has been isolated from more than 99% of all cases of cervical cancer. 1 Of the 200 distinct HPV genotypes that have been identified to date, 40 are known to be associated with genital infection, and about 30 types have been isolated from women with cervical cancer. 2 High-risk HPV types include HPV 16 and 18, and it is these types which are responsible for the majority of cervical cancers. 2 HPV types 6 and 11 can lead to anogenital condylomata acuminata (genital warts) 3 ; a potentially significant medical problem.The incidence of cervical cancer in the Latin American region is among the highest in the world 4 (33.5 cases per 100,000); even higher than other developing regions and countries such as subSaharan Africa (31.0 cases per 100,000) and South central and Southeast Asia (18.3 cases per 100,000). 5 The highest incidence rates are observed in Haiti (87 per 100,000), Bolivia (55 per 100,000), Peru (48 per 100,000) and Nicaragua (47 per 100,000), and the lowest rates are reported from Argentina (23 per 100,000) and Uruguay (19 per 100,000). 6 Each year near 493,000 new cases of invasive cancer of the uterine cervix are diagnosed; 83% of which ( 409,000 cases) occur in developing countries and 18% ( 86,000 cases) specifically in Latin America (Central America, South America and the Caribbean). 7 Acquisition of HPV infection starts with the onset of sexual activity and can be as high as 42.5% after 4 years of follow-up as was observed in a cohort of Colombian women between 15 and 19 years of age. 8 The prevalence of HPV infection in women with normal cervical cytology in Latin America has been reported to range from 14.5 to 16.6%. Literature suggests a prevalence of HPV of 14.5% in Morelos, Mexico, 9 14.8% in Bogota, Colombia, 10 14.0% in Santiago, Chile, 11 16.6% in Concordia, Argentina 12 and 14%...