In this work, we study the phenomenon of Direct Tunneling(DT) in Metal-nGaN Schottky junctions. We first compare tunneling current densities computed using quantum (NEGF) and the semi-classical (WKB) transport formulations, based on a single band parabolic approximation to the complex GaN bandstructure. We then estimate current densities using the WKB transport formulation, with complex bandstructures extracted from the two band k·p and four band k·p theories of the wurtzite GaN. We find that a WKB transport formulation is quite reliable for low bias values. We also find that the use of multi-band k·p models for calculating tunneling effective mass is necessary to estimate tunneling current densities accurately. © 2012 IEEE.