The electron transport physics within the conduction-band of resonant tunneling diodes with staggered-bandgap structure is analyzed. Here, the current-voltage characteristic for AlGaSb/InAs/AlGaSb double-barrier tunneling diodes is calculated in the framework of the six-band Kane model. This work demonstrates that the conduction-band electron transport is extremely dependent on the coupling between the conduction and valence bands and that an accurate estimate of current density requires the application of a multi-band model. In addition, the application of a multi-band model yields results that are in excellent agreement with existing experimental measurements on staggered-bandgap structures when well known material parameters are utilized. (C) 2002 Published by Elsevier Science Ltd.