Objective   The changes of laboratory data in 2 patients with severe acute respiratory (SARS) were observed and their characteristics were also assessed in the value of development.Methods   The blood routine,biochemical test,T lymphocell subgroup as well as other infection marking in peripheral vein blood were detected in disease course.Results  White blood cell amount of SARS patients have taken on going up after hospitalizing,and returned to normal step by step with treatment.Multinomial biochemical data increased.CD3  +-CD4  +-CD8  + T lymphocell notably reduced,and went up with condition improvement of patients.The antibody of coronavirus in the blood was not shown up until 11th～14th day after onset of illness.Conclusion  CD3  +-CD4  +-CD8  + T lymphocell and lymphocell proportion were important laboratory data of SARS patient whose condition is  serious,and have very vital guidance value for treatment and prognosis judgement.The antibody of the coronavirus is meaningful for retrospectively diagnosis.