Abstract: Objective:To evaluate clinical diagnostic significance of sera specific antibodies in severe acute respiratory syndrome （SARS） patients.Methods:Using ELISA，we determined sera coronavirus-specific IgG/IgM antibodies in 156 SARS patients and analysed the relation between the produce of specific antibodies and the courses of disease.Results:Positive rate of serum IgG antibody was 75.6%（118/156），and that of serum IgM antibody was 41.7%（65/156）.There were 37 cases of negative sera specific antibodies with both IgG and IgM（23.7%）.Positive rate of serum IgG and IgM antibodies rised with the prolong of the courses of disease，but IgG antibodies reached the culmination（94.5%） during the 50th to 60th day of the courses of disease ，so did IgM antibody during the 40th to 50th day of the courses of disease.The difference of antibody positive rate was greatly significant in different courses of disease（P＜0.01）.Conclusions:Determination of sera specific antibodies in SARS patients may be a kind of important diagnostic reference index，but not golden standard at present.Negative cases of both IgG and IgM antibodies can‘t be absolutely eliminated the diagnosis of SARS.