Objective  To study the diagnosis and therapy of severe acute respiratory syndrome (SARS).Methods  The post-treatment statistics of the patients diagnosed with SARS in Nanjng from April 30 to May 30,2003 such as epidemiological examination,clinical symptoms,chest radiography, blood routine,liver and renal function tests,T lymphocyte phenotype and absolute count,etc.were compared with those of pre-treatment.Results  The two patients,28 and 36 years of age respectively, were diagnosed with SARS.There was a history of close contact for both patients.The initial symptom was fever,followed by nonproductive cough and malaise. RNA of the SARS coronavirus was positive in both saliva and blood.The specific antibodies of IgM of SARS coronavirus in blood showed positive on the tenth day from the onset of the disease, so did the specific antibodies of IgG of SARS coronavirus in blood on the 12    th～16    thday. The initial blood cell count showed leukopenia (total white blood cell count 4×10  9 per liter),and lymphocyte count <1.5×10  9per liter and platelet count <100×10  9 per liter in SARS patients, white-cell count and platelet count increased to normal range after 5 days admission,but the lymphocyte count remained abnormal until the 17    thday after admission.Serum alanine aminotransferase and lactate dehydrogenase levels were obviously higher than normal,but decreased after 10 days of treatment.T cell absolute count decreased in SARS patients and was increased to normal range after 21 days.Bilateral involvement was shown in chest radiographs in SARS patients,and progressive pulmonary infiltration was especially prominent on the 5    thto 10    thday after hospitalization.Empirical therapy most commonly included medication of antibiotics and intravenous ribavirin,and immunity improvement.Corticosteroid was used for two patients,and the course was 18 and 24 days respectively.Noninvasive ventilation was applied to one patient,which lasted for 5 days.Both patients survived.Conclusions  SARS is transmitted by close contact.Epidemiological investigation and etiological examination are important for diagnosis. SARS leads to multi-organ damage. Compound supportive management is helpful and effective.