Brucellosis is a disease which infects human by infected animals and can be seen frequently in developing countries. Combination of two antibiotics is recommended in the therapy of this infection. Despite the efficacy of some antibiotics was demonstrated in animal models, the results are not well correlated with relapses seen in the clinical administrations. Therefore, existence animal model needs to be reevaluated by using natural route of exposure instead of intraperitoneal inoculation of the bacteria. Wistar rats were matched by weight and paired so that one rat of pair was assigned as vector while second rat was target. All vector rats in each cage were inoculated with B.melitensis intraperitoneally. The period for naturally transmission of the disease from vectors to targets was presumed to be seven days. At the end of 7 days period, all rats in the target group were infected. As a result, the rout of natural transmission in experimental animal model is more reliable than intraperitoneal inoculation in the field of antibiotic researches which might have well correlations with clinical outcomes.