Albino rats were monocularly deprived for 1.5-13.5 mo after which the electroretinogram was recorded from both the normal and the deprived eyes. The amplitude of the b-wave in the deprived eyes was much lower for most of the intensity range used. This difference results initially from temporary changes in the deprived retina which decrease with stimulation of the deprived eye. There were no significant differences in the amplitude of the a-wave or in the latencies of the a- and b-waves. A mechanism which could account for these results is discussed.