In this study the gene encoding the Shiga toxin (Stx) was cloned from the chromosomal DNA of Shigella dysenteriae serotype 1 (W30864). The Stx gene was located in a 4.5kb EcoRI fragment. The biological assay revealed that the hybrid plasmid pMGC001 containing the Stx gene could produce Shiga toxin. The amount of Stx was 16 times more than that produced by its parent. The cloned strain showed cytotoxic, entorotoxic and neurotoxic activities. The gene for Stx-B subunit was subcloned into a plasmid vector pJLA503 from the plasmid pMGC001. The B subunit could be expressed at high level in E. coli and has been purified in large quantities. The polyclonal and monoclonal antibodies against B subunit were raised. Western blot showed that they could react specifically to the B subunit.