Following the infection of turkey poults with a field isolate of infectious bursal disease virus, antibody levels were examined and reisolation of the virus was attempted. After inoculation at 36 days of age, peak titres in both the inoculated and a contact-exposed group were obtained after 13 days. The titres fell slightly during the next week and then remained level until the experiment was terminated at 91 days of age. Virus was reisolated from faeces from day 3 until day 8 after inoculation in the inoculated group and from day 4 until day 9 in the contact-exposed group. In the inoculated group, virus was recovered from the bursae, spleens and intestines on both days 4 and 6 after inoculation, but the thymuses on day 6 only. No clinical signs were observed.