174 patients suffering from various autoimmune and renal diseases have been followed up for periods of one to four years. Repeated assessment of clinical and immunological activity is indispensable for therapy, prognosis and rehabilitation. Determination of microscopic haematuria by the Addis count proved to be the best indication of clinical activity. Immunological activity was assessed by the CH50, C3 and immunoconglutinine tests, the titer of the anti-glomerular basal membrane antibodies and the inhibition of leucocyte migration. Depending upon the nature and stage of the disease one or more positive tests indicated activity of the pathological process. Consequently, the simultaneous application of several methods is recommended for assessment of immunological activity in autoimmune renal diseases.