We present a Monte Carlo study of shot noise suppression in double barrier nonresonant heterostructure GaAs/AlGaAs diodes. Substantial suppression up to a factor 0.5 is found in agreement with a formula of de Jong and Beenakker [Phys. Rev. B51, 16 867 (1995)] obtained within Langevin–Boltzmann theory. The spectrum of current noise exhibits two resonant peaks before the cutoff region. These peaks are associated with certain features of the carrier motion due to reflections from the first barrier and oscillations inside the GaAs well, respectively. ©1997 American Institute of Physics.