The aims of the present study are to evaluate the difference of the levels of soluble Fas (sFas) antigen between patients with systemic lupus erythematosus (SLE) and healthy controls and to explore whether sFas has a role in either the disease activity or the organ damage in SLE. Serum levels of sFas were measured in 40 Chinese patients with SLE and 15 age-, gender-, and race-matched healthy controls using double antibody ELISA. SLEDAI scores for disease activity were determined. Data of organ and tissue damage was obtained from clinical records. Serum sFas levels were significantly increased in both more active (mean = 8043.8 pg/ ml, P < 0.001) and less active SLE patients (mean = 4820.2 pg/ml, P < 0.001) comparing to the healthy controls (mean = 3253.4 pg/ml). There was also a significant difference in serum sFas levels between the more active SLE patients and less active SLE patients (P = 0.04). But, the levels of sFas didn t correlate with SLEDAI. There was a significant difference in the serum sFas levels between patients with and without CNS disease (mean = 9582.6, 6634.5 pg/ml; P = 0.007). The same was true when patients with and without renal disease (mean = 10972.7, 6520.1 pg/ml; P = 0.019), as well as serositis (mean = 10385.3, 6709.1 pg/ml; P = 0.005) were analyzed. sFas is elevated in sera of SLE patients, especially in patients with active SLE. The elevated levels of sFas in the sera of patients with SLE may be closely associated with damage to the kidneys, central nervous system and serosa. Serum sFas may serve as a predictor of some organ and tissue damage in SLE. The aims of the present study are to evaluate the difference of the levels of soluble Fas (sFas) antigen between patients with systemic lupus erythematosus (SLE) and healthy controls and to explore whether sFas has a role in either the disease activity or the organ damage in SLE. Serum levels of sFas were measured in 40 Chinese patients with SLE and 15 age-, gender-, and race-matched healthy controls using double antibody ELISA. SLEDAI scores for disease activity were determined. Data of organ and tissue damage was obtained. from clinical records. Serum sFas levels were significantly increased in both more active (mean = 8043.8 pg / ml, P <0.001) and less active SLE patients (mean = 4820.2 pg / = 3253.4 pg / ml). There was also a significant difference in serum sFas levels between the more active SLE patients and less active SLE patients (P = 0.04). But, the levels of sFas didn t correlate with SLEDAI. There was a significant differe nce in the serum sFas levels between patients with and without CNS disease (mean = 9582.6, 6634.5 pg / ml; P = 0.007). The same was true when patients with and without renal disease (mean = 10972.7, 6520.1 pg / ml; = 0.019), as well as serositis (mean = 10385.3, 6709.1 pg / ml; P = 0.005) were analyzed. SFas is elevated in sera of SLE patients, especially in patients with active SLE. The elevated levels of sFas in the sera of patients with SLE may be closely associated with damage to the kidneys, central nervous system and serosa. Serum sFas may serve as a predictor of some organ and tissue damage in SLE.