Physiological measures of neural activity in the auditory cortex have revealed plasticity following unilateral deafness. Central projections from the remaining ear reorganize to produce a stronger cortical response than normal. However, little is known about the perceptual consequences of this increase. One possibility is improved sound intensity discrimination. Intensity difference limens were measured in 11 individuals with unilateral deafness that were previously shown to exhibit increased cortical activity to sounds heard by the intact ear. Significantly smaller mean difference limens were observed compared with controls. These results provide evidence of the perceptual consequences of plasticity in humans following unilateral deafness.