The analysis of morphological and histoezymological changes of spinal cord neurons has been performed in outbred dogs following epidural infusion of isobaric 2% lidocaine solution. In the control group the animals received epidural infusion of 0.9% saline. The results obtained indicate the absence of pathological structural and metabolic changes in the nervous tissue after lidocaine application. Certain signs of morpho-functional reorganization were noted in spinal cord neurons of animals in both experimental and control groups. The registered changes were found to vary within the physiological fluctuation limits and are rather indicative of the functional reaction of the studied structures of the nervous tissue to the epidural injections of either saline and lidocaine.