OBJECTIVES: Gardasil9 is indicated for active immunisation of individuals from the age of 9 years against precancers and cancers affecting the cervix, vulva, vagina, anus and genital warts caused by specific HPV-types 6/11/16/18/31/33/45/52/58. Gardasil9 is anticipated to prevent approximately 90% of cervical, vulvar, vaginal and anal HPV-related cancers as well as 90% of genital warts and 75-85% of high-grade cervical intraepithelial neoplasia (CIN2/3). The study objective was to estimate the NNV to prevent a case of disease by vaccinating 12 year old girls in France with Gardasil9. METHODS: The NNV was defined as NNV=1/(r–rv) where r represents the risk of the disease in the absence of vaccination and rv represents the risk of the disease in vaccinees with Gardasil9 over a fixed period of time. rv is defined as rv=r*(1–VE) where VE represents the vaccine efficacy for each considered disease as listed in the SmPC. We assume the epidemiology of HPV related diseases and the current sceening context of cervical cancer remain stable over the time, vaccination of a cohort of 12 years old girls(i.e. HPV-naïve individuals) and a lifetime vaccine protection. Disease incidences and proportion of cases attributed to the HPV-types included in the vaccine were retrieved from Hartwig et al. 2015 and Monsonego et al. 2007.  RESULTS: NNV estimates to prevent a case of cervical, anal, vaginal, and vulvar cancer were respectively 126, 683, 2744 and 3162. Regarding precancers, NNV estimates were 10, 2843, 1168 and 186 respectively to avert a case of CIN2/3, AIN2+, VaIN2+ and VIN2+. Last, the estimated NNV to avert a case of genital wart was 8. Overall, NNV to prevent one case of any indicated cancer is 99; 9 to prevent any indicated precancer and 4 to prevent any indicated disease. CONCLUSIONS: The low NNV illustrate the important benefits expected from the Gardasil9 vaccination program.