Patients on the CYC to MTX protocol (#95-I-0091) who experience a relapse of disease while on MTX maintenance therapy. Relapse is defined by a Vasculitis Disease Activity Index of greater than or equal to 3. Patients from outside the NIH will also be eligible if they have been treated with a CYC to MTX regimen identical to that used in #95-I-0091 and experience a relapse of disease while on MTX maintenance therapy. If treatment for this relapse has already been commenced at the outside institution with daily CYC and glucocorticoid, patients will still be eligible if there is a history of a Vasculitis Disease Activity Index greater than or equal to 3 at the time of CYC and glucocorticoid initiation. Patients who experience a relapse of disease after MTX has been stopped or while tapering the MTX dose (following 2 years of maintenance therapy) will not be eligible.