A study of infectious bursal disease (IBD) or ‘Gumboro disease’ seroprevalence rates in healthy, non-vaccinated indigenous scavenging chickens in northern Tanzania was conducted in November and December 2009 on 362 chickens raised in a traditional management system. Individual bird and flock-level information was collected using a semi-structured questionnaire, and serum samples were screened for IBD virus (IBDV) antibodies using the enzyme-linked immunosorbent assay (ELISA). The study revealed high rates of IBDV antibodies, yielding an overall seropositive rate of 58.8 % and with at least one positive bird detected in 82.8 % (74/90) of flocks. Univariate logistic regression analysis revealed that seropositivity to IBDV varied significantly (χ2 = 16.1, P < 0.001) between the study sites. The flock seroprevalence was found to vary from 37.5 % to 91 % between districts and from 75%to 90%between regions. The results of this study showed that IBD is an endemic and widely distributed disease in northern Tanzania.