The transient regime of electron transport in wurtzite InN subjected to applied electric fields in the Gamma-A and Gamma-M directions is calculated. The strength of the electron drift velocity overshoot effect is shown to be substantially dependent on the field direction, being stronger in the latter than in the former. This behavior is explained on the basis of the energy dependence of the band structure flattening, which is weaker in the Gamma-A than in the Gamma-M direction, and gives rise to a heavier average effective mass. (C) 2002 Elsevier Science B.V. All rights reserved.