Irritable bowel syndrome (IBS) is characterized by chronic recurrent abdominal pain and alterations in bowel habits, unrelated to organic causes. Eosinophils have a role in GIT pathology mediated by inflammatory mechanisms and by classical and non-classical food allergy mechanisms. Eosinophils that infiltrate the epithelium in more than occasional numbers, coalesce to form aggregates, or show extensive degranulation are always abnormal and raise a broad differential diagnosis. We aimed in this work, to study the association between colonic mucosal eosinophilia and IBS patients. The study was conducted on 80 patients who met the inclusion criteria of IBS based on Rome IV symptoms questionnaire. Patients were subjected to thorough general and abdominal examination, basic laboratory investigations, abdominal ultrasonography, lower endoscopy (colonoscopy) and biopsy and histopathological examination. Here in this study, IBS patients diagnosed according to Rome IV symptoms questionnaire. The percentage of IBS was higher among females (71.25%) compared to that in males (28.75%). 62.5% patients was IBS- D subtype and 25% patients was IBS-C subtype. Histopathological results of IBS Patients' biopsies were as follow: 10%. were mainly lymphocytic infiltrates; 15% were eosinophilic infiltrates mainly; 75% were having very few mixed inflammatory cells. 17.5% female patients' biopsies showed eosinophilic inflammatory cells infiltrates compared to that from males (8.7%), which was statistically insignificant. The current study has some limitations which should be noted. It was a relatively small sample size of population were included.