Antineutrophil cytoplasmic antibodies (ANCA)-associated vasculitis (AAV) is a group of necrotizing, small-vessel vasculitides, including three distinct entities - granulomatosis with polyangiitis (GPA), eosinophilic granulomatosis with polyangiitis (EGPA), and microscopic polyangiitis (MPA). AAVs are different for epidemiology, genetics, clinical presentation, and response to treatment. The French Vasculitis Study Group (FVSG) is a group of French investigators taking care of patients with vasculitis, grown up with the aim to improve our understanding of these diseases. Since its foundation, a large national database collecting information from more than 60 French expert centres has been set up. The first study presented is a critical appraisal of the randomized trials conducted on AAV. Here we stressed the need to achieve a better harmonization of eligibility and outcome criteria. We then show the results of three studies on GPA patients from the FVSG database. We have shown a progressive improvement of patient’s overall survival against an unchanged risk of flare in a long-term analysis of about 800 patients recruited over about 40 years. We have also contributed to better characterize GPA patients with peculiar phenotypes, e.g. those with an increased eosinophil count at diagnosis, and those with a disease confined to the respiratory tract (localised GPA). Mild to moderate hypereosinophilia was found in one of four GPA diagnosis, and identified patients with a disease phenotype approaching to that of EGPA, with more neurologic and cutaneous involvement. One of ten patients had a localised GPA at diagnosis, and about 25% of them developed a systemic disease. Compared to patients with a systemic disease, GPA patients with a localised disease displayed more disabling ENT manifestations. The knowledge on GPA has hugely improved during the last years, but additional efforts are needed to further improve our understanding on pathogenesis, classification and management of this rare disease.