The aim of this work was the comparison of reactivation potency of four oxime acetylcholinesterase (AChE) reactivators (pralidoxime, HI-6, K027 and K033) on three resources of the enzyme (human, pig and rat brain homogenate) inhibited by nerve agent sarin. The results demonstrate remarkable differences in the reactivation of inhibited brain AChE, depending on the oxime and species