Background: Women older than 30 years are the main beneficiaries of improved cervical cancer screening with human papillomavirus (HPV) DNA testing. The role of vaccination against HPV types 16 and 18, which is recommended routinely for preadolescent girls, is unclear in this age group. Objective: To assess the health and economic outcomes of HPV vaccination in older US women. Design: Cost-effectiveness analysis with an empirically calibrated model. Data Sources: Published literature. Target Population: US women aged 35 to 45 years. Time Horizon: Lifetime. Perspective: Societal. Intervention: HPV vaccination added to screening strategies that differ by test (cytology or HPV DNA testing), frequency, and start age versus screening alone. Outcome Measures: Incremental cost-effectiveness ratios (2006 US dollars per quality-adjusted life-year QALY gained). Results of Base-Case Analysis: In the context of annual or biennial screening, HPV vaccination of women aged 35 to 45 years ranged from 116950to 272 350 per QALY for cytology with HPV DNA testing for triage of equivocal results and from 193690to 381 590 per QALY for combined cytology and HPV DNA testing, depending on age and screening frequency. Results of Sensitivity Analysis: The probability of HPV vaccination being cost-effective for women aged 35 to 45 years was 0% with annual or biennial screening and less than 5% with triennial screening, at thresholds considered good value for money. Limitation: The natural history of the disease and the efficacy of the vaccine in older women are uncertain. Conclusion: Given currently available information, the effectiveness of HPV vaccination for women older than 30 years who are screened seems to be small. Compared with current screening that uses sensitive HPV DNA testing, HPV vaccination is associated with less attractive cost-effectiveness ratios in this population than those for other, well-accepted interventions in the United States. Primary Funding Source: National Cancer Institute, Centers for Disease Control and Prevention, and the American Cancer Society.