Irritable bowel syndrome is observed mostly in Ukrainian children and may be related to adverse health effects as a result of the Chernobyl disaster. The aim of this study was to determine status of T-cell population lymphocytes in children with clinical symptom of irritable bowel syndrome. The test population consisted of 95 participants: 75 rural patients aged 4 to 18 who lived in a contaminated area exposed to natural environmental radiation with clinical symptom of irritable bowel syndrome (categorized in three groups) and 20 healthy urban participants from Kiev aged 5 to 15 as control group. Internal radiation activity has been measured by -ray spectrometry. Peripheral blood leukocytes were analyzed for T-lymphocytes subset such as T-lymphocytes (CD3+), T-helper (CD4+) and T-cytotoxic...