Background: Brucellosis is one of the most important and common diseases among humans and animals, with great health and economic significance.Objectives: This study aimed to investigate some risk factors of brucellosis infection in Iranian dairy farms.Methods: This study is a herd-level case-control study on dairy farms. Case dairy farms (95 dairy farms) included all registered cases of disease during 14 months of studying with at least one positive serum cow (Rose Bengal, Wright, and 2-mercaptoethanol tests consecutively) and control dairy farms (95 dairy farms) in the condition of at least two disease-free years were selected and matched due to the capacity, and geographical area with case dairy farms. The obtained data were analyzed by the multivariate conditional logistic regression test and SPSS software, version 20.Results: According to the statistical relationship between studying independent variables and brucellosis infection in herd, the hygiene and disinfection of watering points (washing at least three times a week and using detergent or disinfectant) reduce the risk of brucellosis infection (OR=0.04, 95% CI, 0.003%-0.499%) and factors such as the history of abortion (OR=7.01, 95% CI, 1.51%-32.59%), the replacement of livestock from outside (OR=7.87, 95% CI, 1.07%-58.07%) and introducing new livestock during last 12 months (OR=7.27, 95% CI, 1.20%-43.90%) increase the risk of brucellosis infection.Conclusion: More serious attention to rancher training, the observance of hygienic principles, and legal restriction of livestock displacement are among the recommended strategies to prevent brucellosis infection on the farm.