In three patients with the sicca syndrome (Sjögren's syndrome), who were followed for one to seven years, glomerulonephritis developed. None of these patients fulfilled the diagnostic criteria for systemic lupus erythematosus. All of these patients had circulating immune complexes as detected by the Clq binding assay. Glomerular histology by light and electron microscopy revealed changes compatible with membranoproliferative glomerulonephritis in two of the patients and membranous glomerulonephritis in the third. All patients showed rapid improvement in renal function following moderate doses of corticosteroids. In addition, the treatment decreased the level of circulating immune complexes in two patients who were followed for a sufficient period of time.