In order to verify the hypothesis that Italian patients with systemic lupus erythematosus (SLE) may be immunogenetically distinct from SLE patients born in other regions, we investigated the HLA class I and II antigens and their relation with the various autoantibodies characteristic of the disease in an Italian SLE population. Forty-four SLE patients were typed for HLA-A, -B, -C, -DR and -DQ antigens; sera from the same patients were tested for the presence of antibodies to the nuclear or cytoplasmic antigens Ro/SSA, La/SSB, Sm and RNP (ENA). Results of HLA typing showed that the frequencies of DR3 and DQw2 were increased in patients compared with controls. Analysis of the correlations between HLA antigens and anti-ENA antibodies showed that both DQw2 and DR3 were increased in patients with anti-Ro and/or antiLa antibodies, while in patients with anti-Sm and/or antiRNP antibodies the DQw2 and DR4 were found to be increased. Only DQw2 was found to be significantly increased in anti-ENA positive patients. These results might suggest that Italian patients with SLE are, at least in part, different from lupus patients living in other geographical areas and suggest the association of DQw2 with the autoantibody response to ENA in SLE.