Renal biopsy is irreplaceable in the diagnosis, and in particular treatment of patients with lupus nephritis. So far none of the clinical or laboratory parameters can be used to predict the histological finding and in particular the extent of lesions. Biopsy makes a correct definite diagnosis of the renal involvement in SLE possible as well as indication of appropriate treatment. Immunosuppressive treatment based on knowledge of renal histology contributes also, beyond doubt, to a better prognosis of lupus nephritis. On the other hand the role and indication for renal rebiopsy in patients with lupus nephritis is a problem for which there is not yet a definite answer. Careful clinical follow-up and intense laboratory monitoring usually permit early and aggressive treatment of renal relapses of the disease characterized by a rise of serum creatinine or proteinuria; however only repeated renal biopsies permit evaluation of the long-term prognosis incl. important therapeutic decisions in every given case. A good correlation between the clinical picture and histological finding is usually encountered in patients whose condition has improved. An unaltered histological finding is usual in patients with persisting nephrotic syndrome. Conversely in patients with deteriorating renal function the histological finding cannot be predicted. In particular in these patients who run the risk of development of irreversible renal failure renal rebiopsy is not only fully indicated but more or less mandatory to evaluate the necessity or suitability of further aggressive treatment.

        Key words: systemic lupus erythematosus, biopsy, glomerulonephritis, lupus nephritis