To report the presence af ANCA with an unusual polyreactivity.50 year-old woman with pulmonary fibrosis whose immunological investigations showed the presence of ANCA with an unusual polyreactivity against several neutrophil proteins (PR3,MPO, BPI, lysozyme, elastase and cathepsine G) which could be related to a polyclonal hypergammaglobulinemia occurring in this patient.The international consensus on the testing of ANCA recommends seeking major specificities like MPO and PR3 which are good markers of ANCA-associated vasculitides. The use of multiantigenic ELISA can be helpful to detect various target antigens at the same time and may thus explain some atypical fluorescent patterns observed when searching for ANCA by Indirect immunofluorescence, these results, however, must be interpreted with caution.