In this paper we have developed a quantum driftdiffusion (QDD) and quantum energy-balance (QEB) based simulator for scaled nanowire devices. Solving the QDD+QEB along the length of the wire together with Schrodinger equation across its cross-section allows us to take into account the energy quantization, velocity overshoot and tunneling. In addition, the Schrodinger equation reduces the dimensionality of the transport equations. We also discuss the discretization scheme and numerical implementation of QDD and QEB. This was then applied to a specific case of nanowire MOSFET. © 2012 IEEE.