The systemic vasculitides are multi-system disorders with significant mortality and morbidity and frequent relapses. Treatment is usually effective but fraught with potentially serious effects. Disease Assessment is important to ensure that patients receive the appropriate treatment. Disease Assessment should comprise measurement of disease activity, chronic irreversible damage and impairment of function. Serological markers can be helpful in assessing disease activity but lack sufficient sensitivity and specificity to be used on their own. Radiological techniques such as Magnetic Resonance Imaging, Ultrasound and Positron Emission Tomography show promise in the large vessel vasculitides but require validation in large studies. Clinical Assessment tools are the current gold standard for the assessment of disease activity, damage and function.