One-dimensional nanostructures of graphene such as graphene nanoribbons (GNRs) can prove attractive for digital electronics in the form of interband tunneling transistors, as they are capable of high drive currents. Here, we report on the transport properties of p-n junctions formed in GNR field effect transistors (FETs). It is found that the current density in the devices is indeed high; in the 1–1.5 A/mm range have been measured, comparable to Si-MOSFETs and III-V Nitride HEMTs. The observed unique current–voltage characteristics of the double-gated GNR FETs having a lateral p-n junction as their channel is explained by a field-effect model. Due to the lack of sufficiently large bandgap in the 30 nm wide GNR, the device still cannot be turned off completely, but rectification is achieved. The results suggest that the fabrication of tunneling FETs made out of graphene is possible and their characteristics may meet the expectations. Copyright © 2012 John Wiley & Sons, Ltd.