Electric field-induced luminescence quenching in thin films made from common organic electroluminescent material of aluminum (III) 8-hydroxyquinoline(Alq3)is reported. The dependence of luminescence quenching on excitation wavelength and electric field is attributed to field-assisted hopping separation of charge in localized excited states. The effect extrapolated to high electric fields can reduce the luminescence yield by as much as 60&percent; limiting electroluminescence quantum efficiency in high-field-driven light emitting diodes based on theAlq3emitter. ©1997 American Institute of Physics.