This study will examine the use of rituximab in patients with Wegener's granulomatosis (WG) who have experienced a relapse of the disease through standard therapies. Rituximab is an antibody directed against the human protein called CD20, found on the surface of normal and abnormal B lymphocytes. Rituximab decreases the number of B lymphocytes. This study will examine the safety of rituximab in WG and rituximab's ability to reduce the level of circulating antineutrophil cytoplasmic antibodies (ANCA), which are antibodies that react to substances found in white blood cells. ANCA have been found to be strongly associated with WG. The study will also explore whether rituximab can reduce the occurrence of disease relapse. WG is a disease marked by inflammation of blood vessels. It can involve many different parts of the body, including the sinuses, lungs, kidneys, brain, nerves, eyes, intestinal tract, skin, joint, heart, and others. Before the use of cytotoxic drug therapy, WG was almost always fatal if untreated, with a mortality rate of 93% within 2 years.