Dendrimers represent a class of monodispersed synthetic macromolecules with a well defined three-dimensional structure of nanometer dimension in which a series of layered branches regularly extend from a central core molecule. Due to their precise nanoscale sizes, well-defined branched structures, and various surface modifications, dendrimers have been extensively investigated in a wide range of applications in the biomedical field, particularly in the therapeutics and diagnosis of cancer. This article gives an overview of the recent advances of dendrimers and dendrimer-based hybrid nanoparticles for cancer therapeutics and diagnosis applications.