Characteristics of three transmissible gastrcenteritis cro virus field virulent strains (Gut origin : Ames #40, CN and Miller), three low cell culture - jessagerl strains (Ames #40-10, (ThJ-l0andMiller-10), thxeehighcellculture- ssagoistains (SP30, Neb -28 and Miller - 6)), and three vathnal stains (SP, ‘10 and Syntex) were studied to find the differ - enthtion in plaque si in McClurldn swine tests cell or - iture among the four groups of virus stains. There were clure differences in plaque si ummary ehen the stains were c - ompared The viruses of gut origin have plaque s& ra - nging from 0.5 to 2.0mm in diameters, low cell culture - passage! stains have plaque s& ranging from 1.0 to 3,0 mm, high cell culture - passage! stains induce! plaques larger than 3.0 mm, whereas vaccinal stains inducer] plaques that w - ere smaller than l.Omm, Thedatusuggestthattheplaqueme- thcdleusefulas invitromarkerinthe differentiation of TOE virus stains.