The study of functional nervous system state in 53 fire fighters and 31 gas-rescuers, performed using the electroneuromyographic examination including the registration of M-response and F-wave, has revealed the distal disturbances of motive axons of the peripheral nerves. The findings were found to be more often observed in the range of the normative values which corresponded to the latent (clinically not pronounced) disorders. The induced of stimulation electroneuromyography have been revealed which were found to be more significant for studying the toxic disorders of the peripheral nerves.