Abstract: Objective:To analysis the characteristice、affecting factors of peripheral blood WBC of patients with severe acute respiratoy syndrome （SARS）.Methods:Take 37 patients with SARS as examined WBC，CD4⁺lymphocyte，blood and sputum culture periodically，then analyze them with clinical types and therapy with statistic method.Results:About 62.1% patients had high WBC count in （15.675.39） days during their clinic progression，the WBC count averages were （15.7175.92）109/ L，The rate of neutrophil was （84.2±10.9）%，The high WBC were related to clinic types，lower CD4⁺lymphocyte，the uses of hormone and ventilator 22 of 37patients were effecting by the use of antibiotics.Conclusion:The higher WBC count was probavly induced from the secondly bacteria infection or nature progess，and could not been cured by the use of antibiotics.