Hans Friis-Andersen1,2, Thue Bisgaard2,3 1Surgical Department, Horsens Regional Hospital, Horsens, Denmark; 2Steering Committee, Danish Hernia Database, 3Surgical Gastroenterological Department 235, Copenhagen University Hospital, Hvidovre, Denmark Aim of database: To monitor and improve nation-wide surgical outcome after groin hernia repair based on scientific evidence-based surgical strategies for the national and international surgical community. Study population: Patients ≥18 years operated for groin hernia. Main variables: Type and size of hernia, primary or recurrent, type of surgical repair procedure, mesh and mesh fixation methods. Descriptive data: According to the Danish National Health Act, surgeons are obliged to register all hernia repairs immediately after surgery (3 minute registration time). All institutions have continuous access to their own data stratified on individual surgeons. Registrations are based on a closed, protected Internet system requiring personal codes also identifying the operating institution. A national steering committee consisting of 13 voluntary and dedicated surgeons, 11 of whom are unpaid, handles the medical management of the database. Results: The Danish Inguinal Hernia Database comprises intraoperative data from >130,000 repairs (May 2015). A total of 49 peer-reviewed national and international publications have been published from the database (June 2015). Conclusion: The Danish Inguinal Hernia Database is fully active monitoring surgical quality and contributes to the national and international surgical society to improve outcome after groin hernia repair. Keywords: nation-wide, recurrence, chronic pain, femoral hernia, surgery, quality improvement