Abstract: Objective: To study the variation of soluble serum Fas and soluble Fas Ligand in patients with aplastic anemia.Methods: The level of sFas and sFas Ligand in the serum of 30 patients with aplastic anemia were measured by enzyme-linked immunosorbent assay(ELISA).Results: The level of sFas in the patients with aplastic anemia(AA) was apparently lower than that of normal controls(P<0.01),and the level of sFas in the patients with severe aplastic anemia(SAA)was much lower than that of patients with chronic aplastic anemia(CAA)(P<0.05);The level of sFas in AA patients was related to the clinical types and curative effects.The levels of sFas ligand in AA patients and controls had no difference.Conclusions: The level of sFas in AA patients is below the normal.Detection of the level of sFas in AA patients is an effective indication of the condition of the patients.