Mouse blood hemoglobin (Hb) adduction with 4-(methylnitrosamino)-1- (3-pyridyl)-1-butanone (NNK0 was studied by ^1^4C-accelerator mass spectrometry (^1^4C-AMS). The dose range of NNK administered is 0.01 ～3.0μg/kg b.w.. In the exposure of mice to NNK ranging from 0.1 to 3. 0μg/kg b.w., the number of Hb adducts increases with increasing dose elvels with linear relationship in 1g/1g presentation. However, the number of Hb adducts almost keeps no change over a dose range of 0. 01～0.1μg/kg b.w.. As the time elapses, the number of Hb adducts reduces quickly in the first 3 days and no marked decay appears afterwards.

Key words: HEMOGLOBIN, ADDITION COMPOUNDS, NICOTINE