The effect of uncouplers of oxidative phosphorylation on parameters of miniature end-plate potentials of the neuromuscular junction was studied in frogs. In the presence of uncouplers there is a temporary increase in the frequency of miniature end-plate potentials (by 20-30 times) and in their mean amplitude (by 2-3 times). With an increase in the concentration of each uncoupler, the time taken for frequency to increase to a maximum and the time of subsequent decrease of frequency are reduced. By the effectiveness of their action on miniature end-plate potentials, the tested uncouplers of oxidative phosphorylation can be arranged in the following order: carbonyl cyanide-p-trifluoromethoxyphenylhydrazone > carbonyl cyanide-m-chlorphenylhydrazone > tetrachloro-2-trifluoromethylbenzimidazole > dicoumarol > 2,4-dinitrophenol > metanitrophenol. The order of this series is the same as when their action was tested on respiration of mitochondria and on the conductivity of artificial phospholipid membranes. The results confirm the previous hypothesis that the liberation of acetylcholine from nerve endings is associated with adhesion of synaptic vesicles to the membrane of the nerve ending under the action of Van der Waals forces. An increase in the concentration of Ca++ ions, liberated from mitochondria by the actions of uncouplers of oxidative phosphorylation, in the cytoplasm causes screening of the surface-negative charge on the membranes and an increase in acetylcholine secretion.