Organophosphorus nerve agents such as sarin, cyclosarin or tabun are substances originally developed for military purposes. These compounds are able to inhibit an enzyme acetylcholinesterase (AChE; EC 184.108.40.206) via phosphorylation in its active site. AChE reactivators and anticholinergics are generally used as antidotes in the case of intoxication with these agents. In this work, reactivation potency of twenty-one structurally different AChE reactivators was tested in vitro and subsequently, relationship between their chemical structure and biological activity was described. Cyclosarin as an appropriate member of the nerve agents family was chosen to illustrate these relationships.