Abstract: Employing the indirect hemagglutination method and compared with isotopic method, serum anti-ds-DNA antibody was determined in twenty three patients with SLE and nine patients with other connective tissue diseases including mixed connective tissue disease(MCTD), progress systemic scleroderma, Sjogren's syn.drorile and dermatomyositis, Serum ds-DNA antibody has not been found in patients with other connective tissue diseases except one case of MCTD (¹²⁵I-DNA antibody 25u).The determination of serum anti-ds-DNA, antibody is iinportaut for further analysis of the total anti-nuclear antibody, diagnosis of SLE, understanding the condition of the disease and reflecting nephritis. The result's of indirect hemagglutination and isotopic methods are consistent with each other.The latter is more sensitive,but the former is more available for routine,laboratories.