The collection of lung specimen from the united slaughtered house was made ii gross examined as S. E. P. leison. The lung specimen then put into the mortar and used Hank's balanced salt solution to make a homogenate 10 x emulsion and centrifugated (2,500 rpm, 20 minutes), the supernatant fluid filtered with 0.451<印ter membrane. The filtered fluid was intratracheally injected w」th SPF piglets. Alter 25 days, the inoculated p」glets were autopsied, the apical, card」ac, intermediales and anterior of diaphragm lobes of both lungs showed markedly S. E. P leison. We also used the autopsied lung specimen to make the filtered fluid as the method above again and cultured in liquid media under special condition, after 3 blind snbcultured in liquid media, We transferred it to solid media and in」ected intratracheally into SPF piglet again. On the solid media, there were 2 kind of colony, M. hyopueumoniae, M. hyorhinis appeared, The inoculated piglets also showed S. E. P leison.