摘要:Background : To achieve preventive and controlling activities of Brucellosis, we aimed this study as the first prospective cohort survey on brucellosis in Iran. This cohort in different phases from 2016 until 2020 going to investigate about brucella infection in selected population of Famenin, a city located in Hamadan province, west of Iran. Study design: A prospective cohort study. Methods: At the first phase of study, Famenin inhabitants including urban and rural people were studied during September to December in 2016. All identified household’s people referred to specified health centers and clinically visited. Blood sampling was done, then these subjects were joined and the follow-up was initiated. At the next step, taken blood samples were examined using Wright kits and 2ME test for diagnosis the seroprevalence of brucellosis. Participants will be followed up for next years to examine clinical profiles of brucellosis and complete investigation about the main risk factors to reach strategies to control and reduce human and animal brucellosis. Results: In the first phase, according to statistical analysis, 3363 persons including 47clusters were enrolled and considered for future studies. All participants were interviewed and demographic questioners were successfully completed. Finally, 2367 blood samples were entered in serology analysis. The seroprevalence of brucellosis based on serologic titers of Wright and 2ME test was 6.59% (95% CI: 5.62%: 7.66%) and 3.46 %( 95% CI: 2.72%: 4.20%) respectively. Conclusion : In the first phase, an extensive range of data and information were collected as the basic data for following phases of the cohort.