Antineutrophil cytoplasmic antibodies (ANCA) have proved to be useful serological markers for a subset of vasculitic diseases, including Wegener's granulomatosis, microscopic polyangiitis, and the Churg-Strauss syndrome. The pathogenesis of the ANCA vasculitides remains less clear, including what role, if any, genetic factors play in the expression of ANCA-associated diseases. Familial cases of systemic vasculitis have been reported, and a number of studies have addressed HLA associations of Wegener's and microscopic polyangiitis, but the results have been confusing and inconsistent. We report the first case of P-ANCA-positive vasculitis presenting in a Native American father and daughter. Both patients had systemic vasculitis and were P-ANCA positive with anti-myeloperoxidase (MPO) antibodies.