The improvement in survival of the systemic vasculitides with the use of current immunosuppression has heightened awareness of their poor long-term outcome in terms of chronic morbidity and relapse. Assessment of systemic vasculitis is an essential part of its management. Better understanding of the underlying pathophysiology of the antineutrophil cytoplasmic antibody-related vasculitides has resulted in improved assays and may result in more precise serologic assessment of disease. Clinical assessment tools for accurately measuring disease activity and damage have been developed and are reviewed in this article. It is becoming increasingly clear that these clinical tools are practical, effective measures that can assist in the treatment of individual patients and play an important role in clinical trials of systemic vasculitis.