Novel peptide neurotoxins, alpha- and beta-pompilidotoxins (alpha- and beta-PMTXs), were purified from the venoms of the solitary wasps Anoplius samariensis and Batozonellus maculifrons. Their structures were analyzed mostly by MALDI-TOF-MS, which were corroborated by solid-phase synthesis. alpha-PMTX, with 13 amino acid residues and the sequence of Arg-Ile-Lys-Ile-Gly-Leu-Phe-Gln-Asp-Leu-Ser-Lys-Leu-NH2, greatly potentiates synaptic transmission of lobster leg muscle by the presynaptic mechanisms. beta-PMTX, in which the lysine residue at 12 position of alpha-PMTX was replaced with arginine, was more potent than alpha-PMTX.