We describe a new drain current model for nanoscale undoped-body symmetric dual-gate MOSFETs based on a fully consistent physical description. The model consists on a single analytic equation that includes both drift and diffusion contributions. It is built on the basis of the potentials at the surface and at the center of the silicon film evaluated at the source and drain ends. The derivation is completely rigorous and is based on a procedure previously enunciated for long-channel bulk Sol MOSFETs. The expression is a continuous description valid for all bias conditions, from subthreshold to strong inversion and from linear to saturation operation. The validity of the model has been ascertained by extensive comparison to exact numerical simulations. The results attest to the excellent accuracy of this formulation. (C) 2005 Elsevier Ltd. All rights reserved.