To investigate role of eye's sign in the patients with neuropsychiatric systemic lupus erythematosus (NPSLE). The scores of eye's sign in bulbar conjunctival microvascular changes were assessed in all patients according to our criteria. The disease activity was measured with SLE Disease Activity Index (SLEDAI) score. Anticardiolipin antibody (aCL) and hemorheology were performed in patients. The eye's sign and whole-blood viscosity were significantly higher in NPSLE patients than those in non-NPSLE patients. The eye's sign has a correlation with SLEDAI, disease duration, whole-blood viscosity, serum concentration of aCL, and no correlation with erythrocyte sedimentation rate, complement and titre of ANA (Anti-nuclear antibody). Our results suggest that eye's sign plays an important role in active NPSLE. The continuous disease activity promotes the vascular damage through an increasing blood viscosity and the eye's sign reflects well this condition. Checking the eye's sign is an useful indicator in assessment of activity or that of effectiveness in treating (NP)SLE.