We report on the results of our simulations of Γ −X scattering in GaAs/AlGaAs heterostructures, discussing the importance of the mole fraction, doping density, and lattice and electron temperature in determining the scattering rates. We consider three systems, a single quantum well (for the investigation of Γ −X scattering), a double quantum well (to compare the Γ −X−G and Γ −Γ scattering rates), and an example of a GaAs/AlGaAs mid-infrared quantum cascade laser. Our simulations suggest that Γ −X scattering can be significant at room temperature but falls off rapidly at lower temperatures. One important factor determining the scattering rate is found to be the energy difference between the Γ -and X-states.