Laboratory tests for the stability of attenuation markers of recombinant vaccinia viruses expressing HBsAg were carried out with those obtained after repeated passages in primary rabbit kidney cells. In these tests it was determined that recombinant vaccinia viruses preserved the attenuation markers of LC16m0 and LC16m8 strains used as vectors, with stable conservation of HBsAg gene expression. The stability of the recombinant vaccinia virus would add another strategy to the use of attenuated vaccinia virus for the development of recombinant vaccinia vaccine.