The physiological importance of GPCR/ligand pathways is highlighted by the fact that numerous pathologies are attributed to their signaling dysfunction. Over 50% of the pharmaceutical drugs currently used to treat human disease are based on compounds that interact with GPCRs. Apelin/APJ constitutes a novel endogenous peptide/GPCR system proposed to be involved in a wide range of physiological functions. Early evidence suggests that apelin/APJ may hold promise as a target for development of novel therapeutic agents which may counteract a number of pathologies including cardiovascular disease. Despite advances in treatment of cardiovascular disease, incidence, prevalence, morbidity and economic costs remain high necessitating the development of new treatment paradigms.