ANCA-associated vasculitides, including Wegener's granulomatosis and microscopic polyangiitis, are systemic autoimmune diseases with poor prognosis in untreated patients, which can be dramatically improved by current therapeutic modalities. The aim of multi-centre randomized trials of the European Vasculitis Study Group is to optimise and standardise treatment of these diseases. From 1995-2001 our department contributed a total of 40 patients to the trials CYCAZAREM (cyclophosphamide versus azathioprine during remission for generalised vasculitis), MEPEX (plasma exchange versus methylprednisolone for severe renal vasculitis) and CYCLOPS (daily oral versus pulse cyclophosphamide during induction phase for generalised vasculitis). In this paper, we report on the preliminary results of long-term follow up of our patients included in international trials. The mean time of follow-up of the patients was 55.7 months with the patient survival rate of 72% and renal survival rate of 65%. Remission was achieved in 82% of patients, out of which 42% suffered a relapse. In generalised forms of vasculitides, treatment with cyclophosphamide is nowadays established as the standard therapy. The aim, however, is to further minimise its toxic effects by choosing the optimal therapeutic strategies. Complete results of all trials have not yet been published; nevertheless, the preliminary available data have already revealed new potential therapeutic approaches.