The anti-hypertensive agent hydralazine can cause a lupus-like syndrome characterized by serosal inflammation, arthralgias and rashes. The kidneys however are usually spared. The condition is characterized by circulating immune complexes and antinuclear antibodies, whilst antibodies against double-stranded DNA are rare. Hydralazine can also cause a systemic vasculitis with a pauci-immune rapidly progressive glomerulonephritis, which is associated with autoantibodies directed against components of the neutrophil cytoplasm. In this study, ten patients with hydralazine-induced vasculitis had antibodies with specificities for both myeloperoxidase and lactoferrin. We suggest that this particular pattern of autoantibodies, together with antibodies with reactivity against nuclear components including double-stranded DNA, are characteristic findings in hydralazine-induced vasculitis. In addition, renal involvement appears to be more common in this group of patients with vasculitis than in those with the lupus-like syndrome.