In the present work, we theoretically investigate the intersubband relaxation of electrons in quantum well systems during photoexcitation using an ensemble Monte Carlo approach. In particular, we compare with recent experimental results by Hartig et al. (Phys. Rev. B (1999)), in which time-resolved photoluminescence measurements are made of the second subband carrier population after band-to-band excitation in a wide coupled quantum well system. In these experiments, the first excited subband energy is less than the polar optical phonon energy. We find excellent agreement between the simulated decay time of the n = 2 subband, and the experimental photoluminescence decay, although it is difficult to distinguish the pure decay time due to electron-electron scattering versus that due to polar optical phonons caused by carrier heating effects. (C) 1999 Elsevier Science B.V. All rights reserved.