Granulomatosis with polyangiitis (GPA), previously known as Wegener's granulomatosis (WG), is a rare long-term systemic disorder that involves the formation of granulomas and inflammation of blood vessels (vasculitis). It is a form of vasculitis that affects small- and medium-size vessels in many organs but most commonly affects the upper respiratory tract, lungs and kidneys. The signs and symptoms of GPA are highly varied and reflect which organs are supplied by the affected blood vessels. Typical signs and symptoms include nosebleeds, stuffy nose and crustiness of nasal secretions, and inflammation of the uveal layer of the eye. Damage to the heart, lungs and kidneys can be fatal.

The cause of GPA is unknown. Genetics have been found to play a role in GPA though the risk of inheritance appears to be low.

GPA treatment depends on the severity of the disease. Severe disease is typically treated with a combination of immunosuppressive medications such as rituximab or cyclophosphamide and high-dose corticosteroids to control the symptoms of the disease and azathioprine, methotrexate, or rituximab to keep the disease under control. Plasma exchange is also used in severe cases with damage to the lungs, kidneys, or intestines.

The number of new cases of GPA each year is estimated to be 2.1–14.4 new cases per million people in Europe. GPA is rare in Japanese and African-American populations but occurs more often in people of Northern European descent. GPA is estimated to affect 3 cases per 100,000 people in the United States and equally affects men and women.