Background/Aim. In Serbia brucellosis is a primary disease of the animals in the southern parts of the country. The aim of this study was to describe the first outbreak of human and animal brucellosis in the region of Šabac, Serbia. Methods. An epidemiological investigation was conducted to identify a source of outbreak and the ways of transmission of brucellosis infection in human population. A descriptive and analytical epidemiological methods (cohort study) were used. Additional data included monthly reports of the infectious diseases from the Institutes of Public Health and data from the Veterinary Specialistic Institute in Šabac. The serological tests for human brucellosis cases were performed in the Laboratory of the Military Medical Academy; laboratory confirmation of animal brucellosis cases was obtained from the reference laboratory of the Faculty of Veterinary Medicine, Belgrade. Results. Twelve cases of brucellosis were recorded from February 9 to September 1, 2004. Total attack rate was 8.1% (7.5% of males, 14.2% of females). Relative risk (RR) of milk consumption was 8.9 (95% confidence interval: 1.63-13.38), and RR for direct contact with animals was 14 (95% confidence interval: 3.5-55.6). The prevalence of seropositive animals in 33 villages of the Mačva region accounted for 0.8%. Regarding animal species, sheep were predominant - 264 (95.7%). Out of a total number of seropositive animals, ELISA results were positive in 228 (88.7%) of them. Conclusion. As contact epidemics generally last longer, it is probable that the implemented measures of outbreak control did reduce the length of their duration.