Autoantibodies to neutrophil cytoplasmic antigens (ANCA) are associated with numerous chronic inflammatory diseases, particularly, but not exclusively, with primary vasculitides such as Wegener’s granulomatosis, microscopic polyangiitis, or Churg Strauss syn drome. Aspects of clinics and diagnosis, therapeutic options as well as the pathogenesis of ANCA-associated primary vasculitides will be discussed in this book. 10 illustrations, 5 tables.