Systemic vasculitis is characterized by the presence of autoantibodies to neutrophil cytoplasmic antigens (ANCA). The role of T-lymphocytes in systemic vasculitis remains uncertain. In the present study, we attempted to explore the role of T-lymphocytes in systemic vasculitis by measuring the serum soluble interleukin 2 receptor (sIL2R) levels in seven vasculitic patients and comparing the sequential measurements with the titres of ANCA which satisfactorily reflect the disease activity. The serum levels of both ANCA and sIL2R were elevated at clinical presentation. Contrary to ANCA, the serum sIL2R remained elevated in most patients despite clinical remission following immunosuppressive therapy. These findings suggest that T-lymphocytes may be activated in the acute phase of the disease. The finding of elevated serum sIL2R levels in most patients during clinical remission indicates that it is not a good measure of the disease activity and tends to argue against the role of T-lymphocytes as a major effector mediating inflammatory injuries in systemic vasculitis.