We examine the blocking of electrons selectively incident on a GaAs/Al0.22Ga0.78As electron Bragg reflector (EBR) from a GaAs/Al0.3Ga0.7As double barrier resonant tunneling structure (DBRTS). An EBR has a minimum transmittance at a specified blocking energy level, EB. This energy level is varied with respect to a resonant tunneling energy, EINJ, of the DBRTS. We find that the blocking efficiency is decreased as EB moves away from EINJ. To satisfy the Bragg condition, any potential barrier in the EBR must be lower than EINJ. We present experimental evidence of blocking by EBRs and compare it with blocking by potential barriers higher than EINJ. © 2001 American Institute of Physics.