In experiments on frog cutaneous pectoris muscle we have been studied a role of calcium entry on processes of exo-endocytosis of synaptic vesicles with using fluorescent styryl dye FM 1–43 and extracellular recording of miniature end-plate currents (MEPCs). Electrophysiologically we revealed that application of high [K+] (40mM) solution lead to different levels of increase of MEPCs frequency in cases of a) presence of Ca2+ ions (1.8 mM); b) presence of Cd2+ (1 mM) and Ca2+ (1.8 mM) ions c) after preliminary incubation at the BAPTA-AM (50 mkM); d) usage of Ca2+-free EGTA (5 mM) -contained solution. During 5-min exposure of solution "a" vesicle retrieval monitored by FM 1–43 based retrieval assay was stimulated. The exposure of preparation in "b, c, d" solutions during 5–15 min caused the failure of FM 1–43 loading in nerve terminals. Enhancement of exocytosis at the preliminary stained terminals lead to decrease of fluorescence intensity in all cases (a - d). Thus, in presence of extacellular (EGTA), intracellular (BAPTA-AM) chelators or blocker of Ca-channel (Cd ions) the blockade of endocytosis was observed. We proposed that Ca2+ entry is necessary for retrieval of synaptic vesicles.