We calculate gate currents of ultrashort MOSFETs with ultrathin gate oxides for different gate and drain biases by directly solving the Schrodinger, electron-Boltzmann, Poisson and hole-continuity equations. Computations give rise to a subband structure that is populated using the calculated distribution function. The calculated tunneling current versus gate voltage curves show oscillatory structure which reflects quantum effects. For very low drain bias voltages, current is found to be generated from low energy electrons especially from tunneling through the gate/LDD overlap regions. For drain biases at pinch-off, tunneling is significant from low energy electrons near the source, as well as from higher energy electrons near the drain. (C) 2002 Elsevier Science Ltd. All rights reserved.