Objective: Efforts to increase human papillomavirus (HPV) vaccine coverage rates in adolescents include finding ways to improve discussions between clinicians and parents. One potentially important piece of information for these discussions is the HPV vaccination status of older siblings.Methods: A nationally representative online panel was used to conduct a cross-sectional survey of parents of children aged 9 to 17 years in October 2012.Results: Overall, 768 adolescents (35%) had >1 older sister aged 10 to 26 years. Male and female adolescents with an older sister who had received no HPV vaccine doses demonstrated higher rates of having no doses themselves, compared with those who had no older sister or those who had an older sister who had received >1 HPV vaccine dose.Conclusions 1,2 HPV vaccination coverage lags behind coverage for other adolescent vaccines; for example, in 2012, vaccination rates among adolescents aged 13 to 17 years were 85% for the tetanus, diphtheria, and pertussis vaccine, and 74% for the meningococcal vaccine, whereas for the HPV vaccine the rates for Ն1 dose were 54% for females and 21% for males.3 Common reasons for not receiving the HPV vaccine include parental lack of knowledge about the vaccine, belief that the vaccination will promote sexual activity, cost, and lack of a provider's recommendation. 4 Strategies to increase HPV vaccine coverage rates include improving communication between clinicians and families.