Eight week old pigs with low (<x8) or free of hog cholera (HC) antibody were inoculated with twelve field strains of HC virus isolated in Taiwan. Two pigs were used for each strain. The ALO strain was served as control. Two pigs inoculated with Tainan II strain died on day 24th and 26 th PI. All of the pigs inoculated with the other strains died on day 12th to 18th PI. The pigs vaccinated with LPC strain virus were challenged with various field strains of HC virus. All of the pigs were free of clinical sign, but the pigs challenged with Yunlin strain showed fever sign. Only the rabbits inoculated with Tainan II strain virus showed febrile reaction. The rabbits died on day 6 th after injected with Yunlin strain virus. Using the cell culture and fluorescent antibody techniques, the Yunlin strain virus was confirmed to be contaminated with pseudorabies virus. All of the field strain viruses propagated in primary swine testis cell culture showed ,he highest virus content m culture fluid on day 4 th. The virus strains of ALO and Tainan 1\1 were 106.0 and 105.5 TCID50 /ml respectively, and the others were 102.0 -104.0TCID50/ml.