HISTORY AND AIM: Considering the incidence of Irritable bowel syndrome or IBS, present diagnostic tests based on Rome criteria and different pathological findings in Iran, this study.

MATERIALS AND MATERIALS:This research was done clinically and paraclinically on the patients with Rome criteria more than 3 months. Firstly the suspicious patients with lactase deficiency were put aside and then FBS, ESR, BUN, CBC and stool examination for leukocytes, RBC and culture and occult blood test six times were done. The sonography of abdomen and pelvis was also conducted. The patients, then, were studied through Barium Enema with Double Contrast Method. The patients with some problems in these tests were deleted and the rest were studied through colonoscopy and several colonic biopsy.

FINDINGS: Some 80 patients with IBS conditions based on Rome criteria were studied through colonoscopy and biopsy 59.5 percent of which were male and the rest female The commonest age in patients was 20-3-. Lymphocyte infiltrtion in lamina propria was reported in 96.3% and histology was normal only in 3.7% that is against the classic medical books.

RESULTS: In our country (Iran), in the patients with IBS, the pathological findings in colon include lympbocytic infiltration in lamina propria, the reasons of which are:

  a) Opposite to Rome criteria that implies colon pathology is normal and there is only movement disorder, lymphocytic infiltration can also be seen in patients with IBS.

  b) Perhaps What we refer to as IBS in our country based on Rome criteria in medical books is part of a lymphocytic colitis.

  c) Lymphocytes is lamina propria in patients with IBS is an immunological reaction to flora microbe in colon in our country.