Most G protein-coupled receptors (GPCR) are rapidly internalized upon agonist stimulation. From the large number of studies available to date on receptor endocytosis, substantial differences seem to exist among GPCRs in terms of both the molecular pathways of receptor internalization and the biological significance of this process. The aim of this review is to outline common themes in GPCR endocytosis and to delineate true phenotypic variations, which reflect specific necessities for receptor's function.