In the last few years, the carbon nanotube (CNT) field has seen a new direction of investigation growing rapidly, along with the interest of more researchers from diverse fields of expertise interested in this new material in an attempt to exploit their properties in biomedical applications. Here we describe the most recently reported work on the application of CNT for gene encoding nucleic acid (DNA and RNA) delivery purposes by using in vitro and in vivo models. Several groups have now successfully observed the cellular internalisation of nucleic acids with the aid of CNT following very different protocols. The main processes for the internalisation pathways and intracellular release of the nucleic acids are here reviewed. Furthermore, we have just started to see some initial studies of in vivo work using siRNA-CNT conjugates to achieve silencing in tumour tissue. Admittedly, it is still very early days for the technology, but future studies are necessary, and will surely appear, in order to determine the feasibility of bringing the CNT closer to the clinic. © The Royal Society of Chemistry.