Dendrimers constitute a new class of macromolecules having a hyperbranched and perfectly defined structure. The attractive beauty of these nanosized compounds induces since ten years an exponential development of the number of publications devoted to this topic. Most dendrimers are purely organic compounds, but heteroatom-containing dendrimers also play a role in the development of this field. Among them, dendrimers having phosphorus derivatives, either at each branching point or only in part of the structure (either on the surface, or at the core, or at special places within the structure), occupy a special place. Indeed, the well-known ability of phosphorus derivatives, especially phosphines, to react with organometallic compounds is also applicable to dendritic derivatives of phosphorus. This particular aspect of phosphorus dendrimers, which undergoes a significant development since 5 years, is the subject of this review. The organometallic derivatives can be grafted either to the surface of the dendrimer, or at its core, or throughout the structure, or only at particular places within the structure. Direct phosphorus-metal linkages, but also phosphorus-metal linkages through one atom will be considered. Most of these macromolecules were synthesized for studying their catalytic properties, this important application is emphasized at the end of this review.