Ste vesicular disease (SVD) and hog cholera (HQ viruses were pxeapitatl with amnoniurn sulfate or pc4yethylene glycol (PEG, MW 6,(U)) at 410 .SVD virus fluid ixealwith8% (wN)ofPEGat4t for3hourswasfoundthelestconcenixationfor pxipition. The rovery rate alnct reached to 1(0%. However, at the same oondihon but treati for 18 hours, the recovery rate of SVD virus was pcx)r, only 5.6%. 8% of PEG was also found excellent concentration for nsoipitation of HCV at 410 either for 3 or 18 hours dcd. Ammonium sulfate was found pxx for the precipitation of SVD and HC viruses.