Three-dimensional Quantitative Structure-Activity Relationship models were designed for irreversible and reversible acetylcholinesterase inhibitors by molecular modeling methods. In case of irreversible inhibitors CoMFA (the comparative analysis of molecular fields) or CoMSIA (the comparative analysis of indexes of molecular similarity) descriptors together with HYBOT 3D fields provide more statistically valid 3D-QSAR models. This indicates importance of donor-acceptor interactions for irreversible acetylcholinesterase inhibition. In case of reversible organophosphorous inhibitors good quality model for structure-activity relationships was developed using CoMFA fields. The obtained models have good predictive power and can be used for estimation of new organophosphorous compounds inhibitor activity that in turn correlates with toxicity of these compounds.