Antineutrophil cytoplasm autoantibodies (ANCA) are essential for the diagnosis of small-vessel vasculitis. Information for and against their usefulness to predict relapse exists. Different approaches, using various methods and definitions, have been used to answer the role of ANCA in predicting disease relapse. Multinational, multicentric prospective studies are needed to address this question using uniform definitions and preferably the best latest tools for ANCA detection.