The most outstanding feature of eukaryotic cells is compartmentalization by membranes, which enables them to achieve a broad spectrum of functions; some of them are common to all cell-types and others are specific to certain cell-types. Individual compartments, namely organelles, have unique sets of proteins that are specifically delivered from one compartment to another by membrane traffic. During the past several years, combinations of genomic, proteomic, structural and real-time imaging analyses with conventional genetical, biochemical and cell biological approaches have provided us with much new information not only about the intricate pathways and sophisticated regulatory mechanisms of membrane traffic but also about integration of membrane traffic with other cellular functions such as signaling and morphogenesis. This Minireview series composed of eight articles highlights the recent progress in this rapidly expanding research field.