Evaluation of the peripheral auditory system was attempted in 81 infants and children using an electrophysiological response, the brain stem auditory evoked response (BER). These measurements, which were successfully made in all cases, were supplemented with impedance measures in some subjects. Results were compared with previous and follow-up audiograms whenever possible. The BER test proved to be a highly reliable diagnostic tool when used in assessing "difficult-to-test" patients. It also identified new patients with peripheral auditory abnormality who subsequently received confirming conventional audiological tests. The BER test results correlated well with the impedance measurements, but some rare instances of important discrepancies require further study.