An electroneurographic method is used for examining 60 agricultural workers at the beginning and the end of the season of spraying with organophosphorus pesticides. At the end of the season (in comparison with the beginning a significant increase of the amplitude of the evoked potential is established as well as a decrease in the velocity of performance at stimulating the motor fibres of n. medianus, and in the velocity of conducting of n. peroneus. The electroneurographic method could be used with success for monitoring the effects of exposure to organophosphorus pesticides.