This observer-blind study compared the prophylactic human papillomavirus (HPV) vaccines, Cervarix™ (GlaxoSmithKline) and Gardasil® (Merck), by assessing immunogenicity and safety through one month after completion of the three-dose vaccination course. Women (n=1106) were stratified by age (18–26, 27–35, 36–45 years) and randomized (1:1) to receive Cervarix™ (Months 0, 1, 6) or Gardasil® (Months 0, 2, 6). At Month 7 after first vaccination, all women in the according-to-protocol cohort who were seronegative/DNA negative before vaccination for the HPV type analyzed had seroconverted for HPV-16 and HPV-18 serum neutralizing antibodies, as measured by pseudovirion-based neutralization assay (PBNA), except for two women aged 27–35 years in the Gardasil® group who did not seroconvert for HPV-18 (98%). Geometric mean titers of serum neutralizing antibodies ranged from 2.3–4.8-fold higher for HPV-16 and 6.8–9.1-fold higher for HPV-18 after vaccination with Cervarix™ compared with Gardasil®, across all age strata. In the total vaccinated cohort (all women who received at least one vaccine dose, regardless of their serological and DNA status prior to vaccination), Cervarix™ induced significantly higher serum neutralizing antibody titers in all age strata (p