Objectives: To measure vaccination coverage among adolescents aged 16–18 years who participated in the National Defense Preparation Day in the Aquitaine region using the free electronic immunization record. Patients and methods: We included adolescents aged 16–18 years who participated in the National Defense Preparation Day in the Aquitaine region from April to October 2013. All participants received a letter explaining how to create an electronic immunization record. These records were then validated by cross-checking the data against the copies of the vaccination cards brought by participants on the day they attended. Vaccination coverage was estimated for eight vaccinations based on the cumulative number of doses recorded and the vaccines recommended during childhood. Results: Among the 18,714 participants, 9,636 agreed to create an electronic immunization record, of which 2,781 were validated. Vaccination coverage was >90% for tuberculosis, diphtheria-tetanus-poliomyelitis, measles-mumps-rubella, and Haemophilus influenzae type B, and <90% for pertussis, hepatitis B, meningococcal C disease, and human papillomavirus. These coverage rates were close to those reported in other available sources. Conclusion: Our study highlights the insufficient vaccination coverage among adolescents for pertussis, HBV, meningococcal C disease, and HPV. The lack of a system that routinely tracks the vaccination status of this population is a major public health issue in France. The use of an electronic immunization record was innovative, but this tool is not widely used in the general population and has been evaluated by Santé publique France (the French national public health agency).