As autoantibodies are thought to participate in the pathogenesis of renal inflammation in systemic lupus erythematosis (SLE) we investigated associations between serological markers of disease activity in SLE and the activity of renal histopathological lesions in thirty-five patients with lupus nephritis (LN). We found the following prevalence of serum auto-antibodies in LN: IgG antinuclear antibodies (ANA) 100%, IgM ANA 69%, IgA ANA 60%, IgG anti-dsDNA 60%, IgM anti-dsDNA 71%, IgA anti-dsDNA 60%, anti-RNP 20%, anti-Sm 14%, anti-SSA 31%, anti-SSB 14%, anti-histone 37%, anti-cardiolipin 80% and antibody to ribosomal protein (anti-P) 6%. No correlation was found between serological parameters and the WHO-classification of biopsies. The activity-index of histological lesion, assessed according to the NIH-renal histology scoring system, correlated with IgM ANA and IgM anti-dsDNA titers. Of all the specific features of histological renal inflammation, glomerular proliferation showed the best overall correlation with serological parameters of disease activity. Anticardiolipin antibodies were correlated with overall disease activity, but not with renal histological activity. Thus, serological markers of disease activity did not adequately reflect the amount of renal inflammation in LN and cannot replace renal biopsy as a diagnostic tool.