Granulomatosis with polyangiitis (GPA) (Wegener) is a necrotizing vasculitis combining inflammation of the vascular wall and peri- and extravascular granulomatosis. Clinically, GPA is characterized in its full form by ENT signs, lung, and kidney involvement. One of the key features of GPA is the presence of ANCAs–cytoplasmic in approximately 90% of systemic forms and in 50% of localized forms–directed against proteinase 3 in most cases. PR3-ANCAs are highly specific to GPA and therefore have a high diagnostic value. Treatment of GPA is based on a combination of corticosteroids and cyclophosphamide or rituximab, which allows remission to be achieved in more than 80% of cases. Azathioprine was the most widely used maintenance treatment, but low-dose semi-annual rituximab maintenance infusions further decrease relapses with acceptable safety. Nevertheless, relapses occur in more than 50% of cases. One of the biggest treatment challenges is the occurrence of side effects, the severity and frequency of which are often linked to the prolonged treatment course, which is difficult to avoid.