Background: Campylobacteriosis is an important public health problem. According to the data from the Croatian Institute of Public Health, there is a continuous increase in the number of positive cases of campylobacteriosis in Croatia. Objectives: The aim of this study was to determine the incidence of campylobacteriosis, seasonal distribution of this disease, and demographic characteristics of affected people. Furthermore, the aim was to complete the biochemical identification of Campilobacter in campylobacteriosis patients. The survey was conducted in Osijek-Baranja County from 1st April 2013 until 31st March 2014. Study design: Prospective cohort epidemiological study Participants and Methods: The study stool samples were analyzed based on patients’ medical references. The survey included 221 respondents from Osijek-Baranja County. Samples were sorted by age, sex, gender, and type of Campylobacter. Demographic data on respondents and data on the month of the illness occurrence were obtained from the archives of the Institute of Public Health of Osijek-Baranja County. Methods used to determine the presence of Campylobacter in the stool were: oxidase test, hippurate hydrolysis test, and antibiotic susceptibility test. Results: The average age of respondents was 16.46±20.00 years. There were more men (52.9%) affected than women (47.1%). The largest number of the affected respondents belonged to the age group 1 to 18 (71%). The highest incidence of campylobacteriois seems to be in June (16.3%) and the lowest in January (3.6%), while the highest number of patients was registered in summer (35.3%) and the lowest in winter (13.1%). In all age groups C. jejuni (92.8%) occurs most commonly. Conclusion: The study indicated that campylobacteriosis is a very significant cause of gastroenterocolitis in Osijek-Baranja County. The incidence of campylobacteriosis (221) is more than twice as common as salmonella (96).