Abstract: The serum level of sialic acid (SA) of 47 patients with systemic lupus erythematosus (SLE)was determined. The results showed that the SA level of SLE patients was significantly elevated when compared with normal controls (P<0.001). The SA level paralleled with the severity of proteinuria, decline of serum albumin and elevation of α₂ globulin. There were no correlations between SA level and the severity of disease and multiple immunologic parameters. Thus the serum SA level is an in appropriate parameter of the severity and acivity of SLE. The mechanism and significance of the elevation of serum SA were discussed.