Over the years, many antibodies have been successfully generated to treat patients with life-threatening diseases, most notably cancer. While the first generation of antibodies, originating from mice, caused severe side effects and were relatively inefficient, technological advances have made it possible to obtain fully human antibodies for therapeutic use. 'Heavy-chain only' antibodies have recently been discovered in the blood of camelids. Because of their size, the antigen-binding units of these antibodies comprising only a single Ig fold are called Nanobodies. These antibody fragments have several remarkable features that make them ideal candidates as next-generation cancer therapeutics. Particularly appealing is their ability to simultaneously inhibit various crucial growth factor receptors or their ligands with a single molecule. In addition, they are easy to clone and express on the tip of filamentous phage, which opens the possibility to select for Nanobodies inducing particular biological effects. Nanobodies have potential to become important cancer therapeutics in the near future, displaying unequalled and unprecedented efficacies in treatment.