The transfer of radiocesium from blood to the lumen of individual sections of the gastro-intestinal tract was quantitatively determined. The water suspension of ion exchange resin was injected to the lumen of the individual sections of the gastro-intestinal tract. The sections were ligated. The highest amount of radiocesium absorbed to the resin in the lumen of gastro-intestinal tract was observed 3 hrs after intravenous administration 137CsCl and reached 17.7% of the administered dose. It was shown that the small intestine and the ileum play the biggest role in absorption and excretion of the radiocesium. The role of the duodenum, the large intestine and the stomach is much smaller in this process.