Adverse health effect of low radiation is clear. The aim of this study was to determine effect of internal low radiation on innate immune status in Ukrainian children with spastic colitis as a result of Chernobyl disaster. The test population consisted of 95 participants: 75 rural participants with clinical symptom of irritable bowel syndrome, aged 4 to 18, who lived in a contaminated area exposed to radio nucleotide due to the disaster in reactor in Chernobyl nuclear power plant (categorized in three groups) and 20 healthy urban participants from Kiev, aged 5 to 15, as the control group. Internal radiation activity has been measured by gamma-ray spectrometry. Peripheral blood leukocytes were analyzed for CD16(+) subset, serum concentration of circulation immune complex was measured by the polyethylene glycol method. Phagocytic activity function was assessed by using latex article and phagocytic index were calculated. p < 0.05 was considered significant. Percent of CD16(+) cell in groups II and III increased significantly in comparison to control group (p < 0.05). Concentration of circulating immune complexes increased significantly in all study groups compared to control group (p < 0.001). Phagocytes activity and phagocyte index decreased significantly in all study groups in comparison to control group (p < 0.001). The innate immune status of study groups has changed. Our data have demonstrated that this change may be related to radioactivity from technogenic pollution due to the disaster in reactor in Chernobyl nuclear power plant.