An unusual case is described of a patient with both anti-glomerular basement membrane (GBM) disease and anti-neutrophil cytoplasmic autoantibodies with myeloperoxidase specificity (MPO-ANCA) presenting with acute renal failure. Four years before a seronegative arthritis of the left wrist was diagnosed. Tests for ANCA by indirect immunofluorescence were repeatedly negative. The diagnosis was made by renal biopsy and by testing the serum with specific enzyme-linked immunosorbent assays (ELISA) for MPO-ANCA and anti-GBM antibodies. To our knowledge, this is the first patient presenting with such findings in the Dutch literature.