Tehran University of Medical Sciences Journal of Medical Bacteriology 2251-8649 11 5-6 2023 11 26 38 48 Fereshteh Ghanbari Department of Laboratory Science, Chalous Branch, Islamic Azad University, Chalous, Iran Haniyeh Fakhar Department of Human Geneticse, Science And Research Branch, Branch, Islamic Azad University, Tehran, Iran Saeed Alamian Department of Brucellosis, Razi Vaccine and Serum Research Institute, Agricultural Research, Education, and Extension Organization, Karaj, Iran Babak Shaghaghi Department of Laboratory Science, Chalous Branch, Islamic Azad University, Chalous, Iran 2023 06 05 2023 11 24 Background:        Brucellosis is one of the most prevalent and common diseases between humans and animals.Prompt diagnosis and timely treatment of this disease can prevent many complications.  In this regard, this study aims to comparatively evaluate ELISA, PCR and serological methods to identify Brucella abortus. Methods:       In this study, the serum of 100 patients referred to Tonekabon private laboratory from  July 2020 to January 2021 was examined by PCR, ELISA and Wright, Coombs Wright, and 2ME methods for the detection of Brucella abortus. Results:      In this study, the mean age of the sample was 43.3 ± 18.2 of which 21% were infected with Brucella abortus according to the above serological methods. According to ELISA test, 22% of the samples were IgM, 6% of the samples were IgG and 16% were PCR positive. Kappa agreement coefficient in Wright and Coombs Wright test and 2me were significant (P <0.001). Serological diagnostic indices and ELISA sensitivity were 68.75% and 68.75%, respectively. The lowest prediction rate of Brucella abortus among diagnostic methods was related to Elisa (IgM). Based on Fisher's exact test, there was no significant relationship between the percentage of Brucella abortus positive PCR cases and age, sex, previous history of infection with Brucella, fever, body aches and dairy consumption. Conclusion:      Based on the results of our study, the accuracy of all methods is comparative and the lowest accuracy is related to Elisa (IgM) which has a lower level of predictability than other methods. The highest level of prediction belonged to Wright and 2me tests. https://jmb.tums.ac.ir/index.php/jmb/article/view/491