A patient had hereditary angioneurotic edema coincident with systemic lupus erythematosus. This condition resulted in loss of hair, arthralgia, leukoplakia, collitis, and a nephrotic syndrome due to proliferative glomerulonephritis. The renal lesion was resistant to treatment with high-dose prednisolone and cyclophosphamide; however, sustained remission occurred after plasmapheresis. The patient has remained well for over two years since this procedure.