The effects of tone stimulus frequency on the auditory P3 of normal younger (n = 16) and elderly (n = 23) subjects were assessed using latency and amplitude measures. Because presbycusis is prevalent among the elderly, it was hypothesized that P3s of elderly subjects elicited by a 2000 Hz target tone would show longer latencies and smaller amplitudes than those elicited by a 500 Hz target tone. As hypothesized, the results indicated that elderly subjects showed prolonged P3 latencies under a 2000 Hz, as compared to 500 Hz target tone condition, whereas younger subjects did not show such latency differences. The P3 amplitudes of the younger and elderly groups were not, however, affected by target tone frequency. The implications of these findings in clinical geriatric ERP research are discussed.