To identify the pathogen of severe acute respiratory syndrome (SARS ), suckling mice and Vero E6 cells were inoculated with the lung samples from autopsied patients with SARS. The tissues obtained from mice were examined with light microscopy and electron microscope(TEM). The infected cells and supernatants were also examined under TEM. The primary hiatopathological leisions in the lungs were wall of lung alveolies thickened and alveolar cavities narrowed. The hepatocytes were swollen and undergone vacuolar and hydropic degeneration. A large quantity of coronavirus like particles could be observed in the infected cells and supernatants and also in mouse pneumocytes under TEM. The viruses are round with diameters 80～120nm.The isolated coronavirus was associated with the current SARS epidemics.