This review covers some epidemiological aspects that allowBrucellato survive, spread, and maintain itself in the environment. Because the success of maintainingBrucella‐free herds is determined by the efficiency of the serological tests to detect a single infected animal the limitations of the traditional serological tests are emphasized. Serological tests cannot differentiate between cattle infected withBrucellaand cattle infected with microorganisms that serologically cross‐react withB.abortusantigen. These cattle and cattle with ‘natural’ antibodies jeopardize theBrucella‐free status of a herd. Likewise, infected cattle with serologically inconclusive test results or which elude detection are also a hazard toBrucella‐free herds. Since cattle that elude detection with serological tests and the presence of non‐specific serum antibodies in healthy cattle have long been recignized as problems, it is opportune to reconsider the procedures currently used to diagnose brucellosis in individual animals. Use of the skin delayed‐type hypersensitivity test in addition to serological tests will significantly improve the diagnosis of brucellosis. This will limit the financial loss incurred by outbreaks of brucellosis.