The efficacy of a novel vaccine, infectious bursal disease virus-antibody complex vaccine (IBDV-Ab), was compared with that of a commercial IBDV vaccine in Shiqiza broiler with maternal antibodies against IBDV. Seventy-five birds were divided into four groups and raised in isolation units. Birds of group 3 and 4 were vaccinated at 10 days with IBDV-Ab vaccine and commercial vaccine, respectively, whereas chickens of group 1 and 2 were not vaccinated with any vaccine. The antibodies against IBDV were measured by enzyme-linked immunosorbent assay (ELISA) before and after vaccinations. All the broilers of groups 2, 3, 4 were challenged with a virulent IBDV strain at 35 days of age. The mean ELISA titres (ET) of group 3 and 4 at 21 days of age were 738 and 946, respectively, and these at 31 days of age were 2 403 and 1 700. After challenge, mortality of groups 2, 3 and 4 were 50% 1 5% and 10% , respectively. The results showed that the efficacy of vaccination with IBDV-Ab vaccine was better than that with commercial vaccine. The data herein suggested that being mixed with antibody against IBDV increase the efficacy of IBDV live vaccine.