Abstract From the extract of 3991 venom glands of the most common European wasp species Paravespula vulgaris a novel basic pentadecapeptide was isolated and investigated by amino acid analysis, micro-Edman-degradation and fast atom bombardment mass spectrometry. The peptide has the sequence H-Ile-Asn-Trp-Lys-Lys-Ile-Lys-Ser-Ile -lle -Lys-Ala-Ala-Met-Asn and exhibits strong mast cell degranulating activity similarly to the mastoparans isolated from various wasp species.