Previous economic analysis of brucellosis control in Mongolia provided a basis for further research. It was observed that there was a long tradition of brucellosis control in Mongolia but little knowledge on its effect on the spread of disease. This thesis addressed this gap and analysed the relationship between stated surveillance policy, the brucellosis prevalence in animals, and the brucellosis incidence in humans. The aim was to contribute to better understanding of the brucellosis surveillance policies applied in Mongolia and their effectiveness, and to draw conclusions and recommendations for control of brucellosis. Four aims were formulated providing steps for investigating the research question. The first two aims focused on (i) the establishment of the epidemiological patterns of brucellosis in Mongolia over the time period 1966 to 2002, and on (ii) the provision of a historical overview of the different strategies applied to the control of brucellosis in Mongolia over the same time period. The third aim was to assess the interactions between the spread of brucellosis and the surveillance strategies, and finally the forth aim was to issue recommendations about future surveillance policies for brucellosis. It was found that the published figures reflected the Brucellosis abortus incidence in the population that could be serologically tested. However, the population at risk (herders) with the main burden of disease, and suffering from Brucellosis melitensis, was underdiagnosed and not treated properly, additionally, the immunisation cam- paigns in small ruminants did not reach the critical vaccination level for eradication. Therefore, the diagnosis and treatment of Brucellosis melitensis in humans has to be assured at Soum (district) level. The current immunisation campaign has to be monitored and evaluated, and the knowledge of brucellosis in humans has to be recognised by policy makers, physicians and general population.