The review provides data on the anticholinesterase activity of 58 specially synthesized thioxy acids of phosphorus containing acetylene bond in the thioester group. Compounds containing acetylene grouping in the - and especially in the -position of the thioester radical have been found to exhibit an inhibitory effect many times greater than their limit (saturated) prototypes. At the same time, as a result of the interaction of acetylene organophosphorus inhibitors with enzymes, a phosphorylated enzyme is formed, as in the case of interaction with saturated prototypes. It is shown that acetylene organophosphorus inhibitors have high biological activity, both for mammals and arthropods. With the replacement of phosphoryl oxygen (PO) with sulfur (PS), the toxicity of acetylene organophosphorus inhibitors for mammals decreases sharply, and for arthropods changes little, which opens up the possibility of obtaining highly selective insecticides .. The mechanism of anti-enzyme action of acetylene FOI and the mechanism of detoxification of diethyl-S-hexinyldithiophosphate are discussed .