In consequence of the invasion of porcine circovirus 2 (PCV2) and teschovirus the situation of pig disease in Taiwan and the control and prevention of pig disease have become more complicated and difficult. The disease situation impairs the finishing rate directly. Reports reveal that PCV2 is associated with certain diseases of pig, e.g. post weaning multisystemic wasting syndrome, porcine dermatitis and nephropathy syndrome, and porcine circovirus pneumonia. Our pig disease service also demonstrates that PCV2 and teschovirus are the number 1 and 2 pathogens being isolated from the specimens of pigs. The role played by these 2 viruses in porcine disease in Taiwan is becoming more important and can not be ignored. Therefore, investigation project involving virus identification on fecal sample taken from the marketing pigs at retention pens in auction markets is urgently needed. Virus isolation, indirect fluorescent antibody staining and polymerase chain reaction technique will be applied for virus identification.