OBJECTIVE: Age is a risk factor for organ damage, adverse events, and mortality in microscopic polyangiitis (MPA) and granulomatosis with polyangiitis (GPA). However, the relationship between treatment and damage, hospitalizations, and causes of death in elderly patients is largely unknown. METHODS: Consecutive patients from Sweden, England, and the Czech Republic diagnosed between 1997 and 2013 were included. Inclusion criteria were a diagnosis of MPA or GPA and age 75 years or more at diagnosis. Treatment with cyclophosphamide, rituximab, and corticosteroids the first three months was registered. Outcomes up to two years from diagnosis included vasculitis damage index (VDI), hospitalization, and cause of death. RESULTS: Treatment data was available for 167 of 202 patients. At two years, 4% had no items of damage. There was a positive association between VDI score at two years and Birmingham Vasculitis Activity Score at onset, and a negative association with treatment using cyclophosphamide or rituximab. Intravenous methylprednisolone dose was associated with treatment-related damage. During the first year, 69% of patients were readmitted to hospital. MPO-ANCA positivity and lower creatinine levels decreased the odds for readmission. The most common cause of death was infection, and this was associated with cumulative oral prednisolone dose. CONCLUSION: Immunosuppressive treatment with cyclophosphamide or rituximab in elderly patients with MPA and GPA was associated with development of less permanent organ damage and was not associated with hospitalization. However, higher doses of corticosteroids during the first three months was associated with treatment-related damage and fatal infections.