It is a common assumption that unilateral hearing loss (UHL) in children is of little consequence because appropriate development of speech and language can still occur with one normal hearing ear. Recent studies, however, suggest that there are significant differences in the cortical processing of sound between children with severe to profound unilateral hearing loss and normal hearing children. Central auditory processing was evaluated in children with UHL using the P300 component of event related potentials. Three groups of listeners participated in this prospective clinical study, listeners with UHL in the right (n=15) or left ear (n=15) and listeners with bilateral normal hearing (BNH) (n=20). Children with right UHL showed a significant reduction in P300 amplitudes in response to speech when compared to a tone stimulus. Comparing speech-evoked P300 response in the three groups revealed a significant delayed latency in the groups with UHL compared with children with bilateral normal hearing. These findings suggest that speech processing is affected in children with UHL whichever its side. The authors also suggested that a right UHL may have a greater impact on the central perception of processing of sound than a left UHL.