INCLUSION CRITERIA:

1. Documentation of Wegener's granulomatosis (WG) or a related systemic vasculitis based on clinical characteristics and histopathologic and/or angiographic evidence of vasculitis. In the absence of histopathologic and/or angiographic evidence of vasculitis, patients who meet one of the following criteria and in whom infectious and autoimmune diseases that may mimic WG or a related systemic vasculitides have been excluded will also be eligible:

   A. A positive assay for anti-neutrophil cytoplasmic autoantibodies (C- or P-ANCA) and the presence of glomerulonephritis defined by red blood cell casts and proteinuria or renal biopsy showing necrotizing glomerulonephritis in the absence of immune deposits.

   B. A positive assay for anti-neutrophil cytoplasmic autoantibodies (C- or P-ANCA) and the presence of granulomatous inflammation on biopsy plus abnormal chest radiograph (defined as the presence of nodules, fixed infiltrates, or cavities) plus nasal/oral inflammation on clinical examination.

2. Age 10-80 years.
3. Evidence of active disease as defined by a Vasculitis Disease Activity Index of greater than or equal to 3 or if begun on CYC and glucocorticoid at an outside institution, a history of a Vasculitis Disease Activity Index greater than or equal to 3 at the time of therapy initiation.

EXCLUSION CRITERIA:

1. Evidence of active infection which, in the judgment of the investigator, is of greater danger to the patient than the underlying vasculitis. In those instances in which infection cannot be ruled out by gram stain and culture of secretions or collections of fluid in involved organs, it may be necessary to obtain a biopsy of the affected tissue for microbiological and histopathological studies.
2. Patients who are pregnant or who are nursing infants will not be eligible. Fertile women must have a negative pregnancy test within one week prior to study entry and must be using an effective means of birth control.
3. Serological evidence of infection with human immunodeficiency virus, hepatitis C, or a positive hepatitis B surface antigen. A serological determination will be performed within two weeks of beginning study participation.
4. Acute or chronic liver disease, past history of alcohol abuse (greater than 14 oz of 100 proof liquor or equivalent per week), ongoing alcohol use of any volume that cannot be discontinued upon entry into the study.
5. History of CYC- or methotrexate- induced pneumonitis with past treatment.
6. Hypersensitivity to CYC, MPM, or methotrexate.
7. Transitional cell carcinoma of the bladder.
8. Inability to comply with study guidelines.
9. Hemocytopenia: platelet count less than 80,000/mm(3), leukocyte count less than 3,000/mm(3), hematocrit less than 20% (in the absence of gastrointestinal bleeding or hemolytic anemia).