In order to examine the efficacy of concurrent vaccination with live and killed Newcastle disease(ND) vaccines two types of each live($B_1$ and LaSota) and killed(gel and oil) vaccines of all commercial origin were administered either alone or simultaneously to day-old broiler chicks having maternal antibody. Live vaccines were given by conjuntival instillation in volumes of 25${mu}ell$ containing $10^{6.0}$ to $10^{6.3}$ median embroy infective dose(EH)) while killed vaccines were given in 0.3$mell$ volumes subcutaneously at the back of the neck Hemagglutination inhibition(HI) antibodies were determined at weekly intervals until 8 weeks of age and protection rate was determined at 4 and 8 week of age by challenge inoculation with virulent ND virus(NDV). During the 8 weeks experimental period concurrent administration of live and oil vaccine produced the highest level of HI antibody and the most satisfactory protection, whereas concurrent rent vaccination with live and gel vaccine induced poor immune responses. There was no noticeable difference in the efficacy between the live vaccines, Bl and LaSota when simultaneously administered with oil vaccine. Except for oil vaccine, single administration of either live or killed vaccine at day-old produced less than 50% protection at 4 and 8 weeks postvaccination(PV). Oil vaucine alone induced 80% and 70% protection at 4 and 8 week PV, respectively. Concurrent vaccination caused on visible side reaction like respiratory symptoms and did not negatively influence the growth rate of birds until the end of experiment.