The action of HI-6 (1-[[[(4-aminocarbonyl)pyridiniol]methoxy]methyl]-2-[ (hydroxyimino)methyl] pyridinium dichloride monohydrate) and obidoxime on soman-induced anticholinesterase and stressogenic effects was studied in rats. HI-6 significantly affected acetylcholinesterase inhibition in erythrocytes, brain and diaphragm and practically eliminated the stressogenic effects of soman, i.e. an increase in plasma corticosterone level and liver tyrosine amino-transferase activity, while obidoxime, on the other hand, had very little influence on soman-induced inhibition of acetylcholinesterase activity and the stressogenic effects of soman. These findings support a hypothesis that the effects of HI-6 are not solely due to reactivation of the enzyme. They also demonstrate its importance in the treatment of soman poisoning in rats.