Objective:The present study has characterized dialyzed toxin from non-O157 VTEC E.coli isolates by vero cell toxicity assay and pathogenecity in mice model.Methods:Toxins from non-O157 verocytotoxic Escherichi-a coli isolated from neonatal calves were characterized.Dialyzed toxin from E.coli O26,O111 and O103 sero-types were prepared and characterized by verocell toxicity assay and pathogenicity in mice model.E.coli O157:H7 considered as positive control for this study.Results:Cytopathic effects in vero cell line first roun-ding of vero cells,followed by clumping of cells and finally disintegrated,blackened,shriveled cell line within 16 to 72 hrs.Phenotypic markers such as hind limb paralysis and reddening of tail were prominent in all the toxicated mice.Extensive histopathological study was conducted for multiple organ involvement.Conclusion:Several methods for toxin assay were developed based on biological,immunological and detection of virulence genes related to toxin production but each test has draw back.Therefore,it is likely that future effort will be focused on the development of assay,which is fast,reliable,specific and sensitive methods based on mice model.