Periviscerokinins (PVKs) are a distinct insect peptide family with unusual distribution in the central nervous system and neurohemal release sites. PVKs were first isolated from the abdominal perisympathetic organs of Periplaneta americana, but can be found in other insect species. Peptides with structural similarity to PVKs have been identified through searches of the Drosophila genome. The cardioacceleratory peptide CAP(2b) of the hawkmoth Manduca sexta shares close amino acid identity with the PVKs and may thus be included as a structural member of the PVK peptide family. In this review, we provide support for grouping CAP(2b) as a PVK family member based on published sequences, and new immunocytochemical findings and mass spectrometric data.