Two patients with systemic lupus erythematosus were studied whose sera contained precipitating antibodies to a soluble cytoplasmic antigen, termed Ro. A reduction in the amount of these antibodies in each case was accompanied by a deterioration in the clinical status with the development of nephritis leading to death. Acid elution of gamma globulin was performed from homogenates of the renal cortex, and in both instances antibodies to Ro were demonstrated in the eluates by double immunodiffusion. The titer of these antibodies was measured in both sera and eluates, and specific enrichment of anti-Ro in the eluates was demonstrated in both patients. This strongly suggests the direct participation of Ro-anti-Ro immune complexes in the progressive renal disease and may underlie the association seen here between the decreasing serum titers of antibodies to Ro and the clinical deterioration in these two cases.