Eightweekoldpigs withlow(<*8)orfreeofhogcholexa (HQ antibcdywexe incailated with twelve field strains of HC virus isolated in Taiwan, Two pigs were used for each stain. The ALD stain was served as control. Two pigs inocu]al with Tainan 2staindialonday24thand26thPL Aflofthepigs incculatlwiththeotherstains died on day 12th to 18th P1, The pigs vaaina1 with LPC strain virus were challenged withvarious fieldstains of HCvirus. A]lofthepigs werefreeof clinicalsign, butthe pigs challenged with Yunlin stain showed virus showed febrile reaction. The rabbit died on day 6th aft inil with Yunlin strain virus. Using the cell culture and fluorescent antibody echniques, the Yunlin strain virus was confirmed to bo conturninaI with pseudorabies virus. All of the field stain viruses gopagated in pirnary swine testis cell culture showed the highest virus content in culture fluid on day 4th. The virus stains of ALD and Taiwan 3 were 10-6.0 and 10-5.5 TCID 5(nl res:&tively, andtheothers were 10-2.0-l0-4.OTCID 5Q”ml.