Wegener's granulomatosis is a systemic vasculitis of the medium and small arteries, as well as of the venules, arterioles, and occasionally large arteries, and primarily involves the upper and lower respiratory tracts and the kidneys. Renal symptoms of Wegener's granulomatosis are indistinguishable from those of vasculitis such as Henoch-Schönlein purpura and microscopic polyangiitis. This case, though initially diagnosed as Henoch-Schönlein purpura, was confirmed as Wegener's granulomatosis from a lung biopsy fifteen years after the initial diagnosis. We report this case with a review of the literature.