In recent years, interest in Wegener's granulomatosis has been stimulated by an increasing appreciation of the chronic relapsing nature of this disease and its association with antibodies to proteinase 3. Although conventional therapy with cyclophosphamide and glucocorticoids has produced remission in most patients, remission may not occur immediately and, in at least 50% of patients, may be followed by relapse. As a result, most patients experience some form of permanent morbidity from disease or treatment, or both. These observations have led to renewed efforts to identify more effective and less toxic therapies. Preliminary studies have evaluated other cytotoxic agents, such as methotrexate, and biologic products, such as high-dose immunoglobulin and monoclonal antibodies. It is hoped that a better understanding of the possible pathogenic role of anti-proteinase 3 antibodies may contribute to improved therapy. Unfortunately, research is handicapped by lack of an animal model, without which it will be difficult to prove convincingly that anti-proteinase 3 antibodies are important in expressing disease.