The paper resented the results of assessing internal dose for 131I by the direct method for Vietnamese objects that was issued in the Intercomparison Program of IAEA. The results on experimental measurements, calculating intake (I) of 131I to thyroid by the specilizing system for measuring thyroid activity, and committed effective dose E(50) using the specializing code of LUDEP 2.0 were shown that the results carrying out at the Nuclear Research Institute (I = 1.48.105 Bq, E (50) = 2.32 mSv) were good and were in accordance with the those of the authors in other laboratories in the world.
