There is growing evidence that pathologic changes in the vascular system are implicated in the pathogenesis of systemic scleroderma. It has been suggested that immune complex deposition may be responsible for such changes. We measured circulating immune complexes in 10 patients with severe systemic scleroderma, 1 of whom had clinical evidence of renal disease, and in 3 patients with generalized morphea. None of the patients had significantly elevated levels. Our findings suggest that although circulating immune complexes are of diagnostic and prognostic value in other collagen vascular diseases, they do not play a major role in the pathogenesis of systemic scleroderma in patients who lack clinical evidence of renal disease.