Clinical trials of oral live recombinant embryonic variola and hepatitis B bivaccine as tablets (Revax-BT) were performed. When volunteers were prevaccinated with oral variola vaccine first in a small dose and, 7, 14, 30, 90, and 180 days later, in a larger dose, a slight reactoginicity was sometimes observed after the first vaccination (with a small dose) whereas revaccination with a larger dose did not give rise to any clinical manifestations. A month after vaccination, a protective level of virus-neutralizing antibodies to vaccinia virus (VV) was observed in 90-100% of the volunteers twice immunized with the bivaccine (in a small dose and in a larger one at an administration intervals of 1-2 weeks under remote revaccination while 6-9 months following vaccination, this level was recorded in 80% of the volunteers. A month following vaccination, 50-55% seroconversion to VV was observed in the volunteers twice immunized with the bivaccine (at an interval of 1 or 3-6 months). Cellular immunity to VV was low (0-20%). Double immunization of volunteers with the oral bivaccine under remote vaccination failed to produce the significant levels of humoral and cellular immune responses to hepatitis B markers. Recombinant VV was not recorded in any blood, saliva, and urine samples taken in the volunteers twice immunized with the bivaccine.