Abstract: Obectives: To aid understanding of the pathogenesis of severe acute respiratory syndrome （SARS）, the novel infectious disease with global impact, and the relation to current therapy. Methods: the Guinea pig was injected with convalescent sera for several times in 24 hours, which were obtained from confirmed SARS patients on average 40 days. artery blood gas was measured and pathological samples were examined by light microscopy.Results: the Guinea pig showed severe acute dyspnea after the third time injection with convalescent serum of SARS patient. partial pressure of oxygen （PO 2） and oxygen saturation were signigicantly decreased while the partial pressure of carbon dioxide was improved, and a pronounced inflammatory-cell infiltrate was seen in the alveoli and the interstitium of the lung pathological samples. Conclusion: Injecting convalescent sera of SARS patients may cause acute damage on the lung of guinea pig.