During the last few years, there has been a tremendous amount of optimism and expectation about nanotechnology and its impact on various fields including medicine and pharmaceutical development. One of the most promising materials being developed during the nanotechnological renaissance we are currently experiencing is the carbon nanotube. Before any biology-related application can even be envisaged, the aqueous solubility of carbon nanotubes has to be resolved. Recently, a variety of methodologies have been proposed which lead to biologically compatible carbon nanotubes. Covalent functionalization of their surface is one methodology, allowing the first attempts towards applications in the field of nanomedicine.