In a recent TiPS article 1 , Juaneda and colleagues reviewed the molecular pharmacology of calcitonin gene-related peptide (CGRP) and related peptides and their receptors. The original CGRP1, CGRP2 receptor classification of Quirion and colleagues was based on a comparison of antagonist affinity using the rat vas deferens and the guinea-pig atrium preparations, which raised the initial difficulty of cross-species comparisons. Juaneda et al. correctly state that this nomenclature ‘is still used by most, if not all, in the field’. However, some important issues relating to this receptor nomenclature should be considered.