Four live virus vaccines against Infectious Bursal Disease (IBD) were studied with regard to their safety, immune response and applicability. None of the vaccines caused clinical symptoms or had an adverse impact on bodyweight. Differences between these vaccins were observed in their effect on the Bursa/ Bodyweight Ratio and the severity of the microscopical lesions of the bursa Fabricii. The immunosuppressive effect of IBD vaccination at one day of age on the response to Newcastle disease vaccine applied was rather low.