Sera from 105 HIV-infected patients were tested for anti-neutrophil cytoplasm antibodies (ANCA) by indirect immunofluorescence (IIF), by specific ELISAs using target proteins of ANCA and by a neutrophil cytoplasm extract ELISA. Forty-four sera were positive. These included 18 positive by IIF, 7 with anti-neutrophil proteinase 3 antibodies, 26 with anti-myeloperoxidase antibodies and 2 with anti-elastase antibodies. Four sera were positive in the neutrophil cytoplasm extract ELISA but not in the specific ELISAs. None of these patients had clinical evidence of a cutaneous or systemic vasculitis. In addition there was no correlation between the presence of ANCA and the stage of disease, intercurrent bacterial or viral infection, anti-nuclear antibodies (ANA) and positive hepatitis B or syphilis serology.