There was an outbreak of human Streptococcus suis (S. suis) infection in southwest China in 2005. The total number of documented patients was 204 and 38 of them died. Four cases were autopsied and are reported in this paper. The autopsies showed that multiple organs were involved, with a prominent injury of the lung, kidney, and intestine. The essential pathologic changes were multiple microthrombi (hyaline thrombi) formation in the capillaries of various organs and tissues, accompanied by congestion and hemorrhage. The pathogen of the disease was S. suis, serotype 2, which was confirmed by means of germ culture of the heart, blood, and tissue samples at the Chinese Center for Disease Control and Prevention (China CDC). The autopsy diagnosis of all four cases was septicemia with disseminated intravascular coagulation (DIC). The cause of death was toxic shock with multi-organ dysfunction. Combined with the epidemic features, clinical manifestations, etiological, and autopsy findings, it accorded with streptococcal toxic shock syndrome (STSS).