Expression of Esyt2^{Scer\UAS.RB.T:Zzzz\FLAG} under the control of Scer\GAL4^RapGAP1-OK6 results in synaptic overgrowth at neuromuscular junctions (NMJ) in third instar larvae: the number of boutons as well as active zones per NMJ is increased as is the neuronal membrane area (active zone density or size is unchanged relative to wild-type controls). The Esyt2^{Scer\UAS.RB.T:Zzzz\FLAG} expression has no effect on synaptic physiology at either either low or elevated extracellular Ca[2+] as neither the frequency not the amplitude of excitatory postsynaptic currents (EPSC) or miniature EPSC is observed compared to wild-type controls. Short-term synaptic plasticity is also unaffected but the Esyt2^{Scer\UAS.RB.T:Zzzz\FLAG}-overexpression confers a resistance to vesicle pool depletion during high frequency (10Hz) stimulation as well as enhanced pool recovery. However, no significant change in the density or distribution of synaptic vesicles within NMJ boutons is observed in these larvae and active zone length as well as T-bar morphology is also normal.