Influence of ethymisol (bismethylamid of 1-ethylimidasol-4,5-dicarbonic acid) on learning and retention of habit was studied in experiments on rats by the method of active conditioned avoidance of electrical stimulation. At the same time optimal conformation form of the drug was determined by the method of proton magnetic resonance and by means of infrared spectra and theoretical conformation analysis. A single administration of ethymisol in the dose of 3 mg/kg reduced the deficit of the avoidance habit, when tested in 30 and 60 days following learning. A stable conformation of the ethymisol molecule with a planar arrangement of atoms of its heterocycle and amide groups was found in which the interaction of this substance with biological macromolecules was most active. The ethymisol effect on the long-term memory apparently results from a stable facilitation of synaptic transmission based on stabilization of spatial structure of biological macromolecules in the given conformation.