A method to purify the hepatopancreat ic parvovirus of penaeid shrimp f rom the infected t issue by density gradient centrifug at ion using potassium tart rate-glycerol as subst rate is described in this art icle. Taken f rom the heavily infected shrimp populat ion, the hepatopancrea w as ground thoroughly and treated w ith 1, 1, 2-t richlorot rifuoroethane or chloroform. After the concent rat ion w ith 6% ~ 8% of polyethylene glycol ( PEG) , centrifugat ion through a sucrose cushion of 35% ( w/ w ) was performed. Then, the resulted pellet w as resuspended and centifugalized through a density gradient of potassium tart rate-glycerol prepared according to Ashley ( 1982) . It is indicated from the purif icat ion result that the method is as effect ive as the CsCl density gradient cent rifugation yet less expensive.