Role of chirality of agrochems. in biolog. activity of pesticides was discussed and exemplified by eantiomers and distereoisomers of malathion, malaoxon and isomalathion as well as 2,4 dichlorophenoxy and 4-chlora-2-methylphenoxy acetic acids and their 2-Bu esters. Methods for seply. racemic mixts. and for asym. synthesis of org. compds. were reviewed.