As hepatitis B virus has a narrow host range in vivo and has not been propagated in cell culture, the application of recombinant DNA methods can, in principle, provide a limitless source of vaccine. One such vaccine, produced from the 22-nm particle form of hepatitis B surface antigen has been found effective in clinical tests. Hence, cloning and expression of only the hepatitis B surface antigen gene have been tried. HBsAg gene was inserted into E. coli vector, pUL 2 and pUC 18 to examine the possibility of cloning and to express the gene. The pUL 2 vector(4.7 Kb) for HBsAg gene cloning was constructed by combining pUC 9, digested with HindIII enzyme, with Lambda DNA fragment(2.0 Kb) digested with HindIII enzyme. The vector now has a single restriction enzyme cleavage site for XbaI enzyme. The pUL 2 DNA was digested with XbaI enzyme and treated with BAP to inhibit the self-ligation. The pUC 18 plasmid DNA was also digested with XbaI enzyme and treated with BAP HBsAg gene fragment(1.8 Kb) derived from pHBV CB plasmid DNA digested with XbaI enzyme was ligated with the above two linear vectors by T4 DNA ligase. The ligated mixtures were used for the transformation in E. coli. As a result of rapid isolation of plasmid DNA, recombinant (pULS, pUCS) were found each transformant and the orientation of the insert DNA was identified by restriction enzyme digestion of the recombinants in the correct direction for the expression of HBsAg gene.