ANCA-associated vasculitides (AAV) are rare, potentially life-threatening autoimmune diseases characterised by systemic inflammation and organ damage. AAV prevalence rates reported in Europe vary considerably and robust data sources are often lacking. This study aimed to examine the feasibility of Claims data analysis as a complementary method to registery-based studies to assess the epidemiology of AAV.In this retrospective observational study, anonymized longitudinal claims data from years 2013-2016 from German statutory health insurance companies (data source: InGef, Institute for Applied Health Research) have been analysed on an age- and gender stratified cohort of ∼3 million persons representative for the German population. In this cohort, granulomatosis with polyangiitis (GPA) and microscopic polyangiitis (MPA) patients were identified.The study cohort revealed a prevalence for GPA and MPA of 210 and 46 cases per million people, respectively. The annual incidence comprised 34 GPA cases and 13 MPA cases per million people per year. Hence, 17 500 AAV patients (GPA and MPA) are estimated to live in Germany, with an annual increase of 3,200 patients. According to their demographic and disease specific characteristics, AAV patients identified in this claims data approach are representative.This is the first study using claims data to assess the epidemiology of AAV. In Germany, AAV was diagnosed more frequently than it was estimated by previous self-reporting registry-based studies. The findings indicate that epidemiological data of AAV may have been underestimated but may also reflect improved diagnostic methods and disease recognition.