A cross-sectional epidemiological study was carried out from September 2004 to March 2005 to determine the seroprevalence of bovine brucellosis in the intensive and extensive cattle production systems of Tigray Region, to identify the risk factors that contribute to the occurrence of brucellosis and assess the public health significance of the disease.rnThe study populations were comprised of indigenous and crossbred cattle in the Region and samples were selected by two-stage cluster sampling. Serum samples collected from 1,951 cattle above six months of age, of which 1,135 from the intensive farms and 816 from the extensively managed herds were screened for Brucella antibodies by the Rose Bengal Plate Test (RBPT) and the reactor sera were further tested by the Complement Fixation Test (CFT). Moreover, information was gathered on age, sex, herd size, management, and agro-ecology of each sampled animal to determine the risk factors for brucellosis seropositivity. Likewise, data on farm or herd-level risk factors and other farm characteristics were obtained using a questionnaire survey, which was administered in person to 112 intensive farms and members of animal owners in the 26 extensive herds. Furthermore, in order to assess the zoonotic importance of the disease, 185 human serum samples were also screened for brucellosis.rnIn this study, the overall seroprevalence of Brucella antibodies in cattle was 1.49%. However, individual animal seroprevalence was found to vary from 0.26% in the intensive farms to 3.19% in animals reared under the extensive management system. Statistically significant difference was observed in seroprevalence values between the intensive and extensive management systems (p