Objective To investigate the expression and significance of CXCL 9 in systemic lupus erythematosus (SLE ) . Methods The level of CXCL9 in peripheral blood from 20 patients with SLE and 20 normal controls were measured by enzyme linked immunosorbent assay .Compare the difference of the expression level of CXCL 9 in peripheral blood between two groups and analyzed their correlation with ages ,duration ,SLE diseases activity index (SLEDAI) .Results The level of CXCL9 in peripheral blood in patients with systemic lupus erythematosus was (1 549 .14 ± 362 .74)pg/L ,but in normal controls was(602 .54 ± 83 .70)pg/L .The level of CXCL9 in peripheral blood in patients with systemic lupus erythematosus was obviously higher than that in controls by statistical analysis ,there was significant difference between the two groups (P<0 .01) .The expression level of CXCL9 in pe‐ripheral blood of patients with systemic lupus erythematosus was positively correlated with SLEDAI (r=0 .892 ,P<0 .01) .Conclu‐sion CXCL9 may be involved in the pathogenesis of systemic lupus erythematosus .