ABSTRACT Background: Crohn's disease and ulcerative colitis are both examples of inflammatory bowel diseases (IBDs) that are chronic GIT diseases of unknown etiology. Aim: This research aimed to ascertain the interleukin-23 serum level in Crohn's disease and ulcerative colitis disease patients. Patients and Methods: The research was a case-control investigation involving 72 participants, subdivided into 48 patients who were either hospitalized in ICU or inpatient wards or outpatient clinics (IBD OPD) in Internal Medicine Department, (Zagazig University Hospitals). In addition, 24 healthy individuals who were age- and sex matched were selected as a control. Results: There were discernible contrasts between the groups with regard to the levels of IL-23. When the two groups are compared, it is clear that there was a considerable distinction between Crohn's disease (CD) in remission and moderate and severe ulcerative colitis. In addition, there was a significant difference between Crohn's disease, which is moderately severe, and ulcerative colitis, which is very severe. There is a large gap between having moderate Crohn's disease and having moderate ulcerative colitis. Conclusion: The findings of this study lend support to the hypothesis that determining an individual's IL-23 levels may be helpful in determining the degree to which Crohn's disease or UC is present. It is possible to postulate that IL-23 is a reliable indicator of the eventual results of the patients. Therefore, it is possible for it to be evaluated with a lower amount of effort and cost compared to other markers and procedures.