Introduction: Brucellosis is a common infectious disease between humans and livestock, which can cause severe economic and health damage to the community. Considering the importance of this study, the aim of this study was to determine the prevalence of brucellosis in Kohgiluyeh and Boyer Ahmad Province in 2017. Materials and Methods: This retrospective cohort study was conducted to determine the rate and causes of brucellosis in Kohgiluyeh and Boyer Ahmad province in 1396. Sampling was done by census. Information about 300 patients with brucellosis, collected from April to July 1996, was collected. In order to collect data from a researcher-made list, data collection for brucellosis patients was used. Descriptive statistics and SPSS 21 series software were used to analyze the data. Results: 17 cases had negative test. The highest number of occurrences in 2016 was 143 cases and the highest occurrence was 171 in the spring. Boyer Ahmad city has the highest rate with 107 cases and Bahmei city with the least amount of brucellosis in 9 cases. 360 people were from rural population. The group of livestock breeders with 147 cases was the most affected and the military group with the least one was the least. Conclusion: By planning properly and timely, you can prevent the disease, complications and dangers of brucellosis.