This study examined individual patterns of the maturation of auditory evoked potential (AEP) in normal infants to determine whether longitudinal data show less variability than cross-sectional data, and to further assess the effect of stage of sleep on AEP. The AEPs for 10 children were examined by repeated testing between the ages of about two weeks and three years. Responses during interstimulus intervals to clicks presented every 2.5 seconds via a loudspeaker to the sleeping child were recorded from electrodes at the vertex referred to joined mastoids. Analysis of the data confirmed earlier cross-sectional findings. General developmental age trends were found in response morphology from birth to three years. All children did show AEPSs to the intensity of the stimulus used in the study, indicating that the presence or absence of the AEPs is important for clinical diagnosis. Data tables are included. (Author/ED)