Auditory and visual P300 recordings were performed on 40 normal, right-handed individuals from age 16 through 65, using 31 evenly spaced scalp electrodes. Amplitude at the P300 peak and latency to this peak at each electrode site were measured. Age was significantly correlated with the 31-electrode mean for auditory and visual P300 amplitudes and auditory and visual P300 latencies. The younger age group (16-40) had shorter auditory and visual P300 latencies than the older group (41-65). Visual P300 amplitudes were of an overall larger magnitude than auditory P300 amplitudes. There were no other differences in P300 amplitudes or latencies by gender, modality, or side of scalp, and no significant topographical differences in P300 amplitudes or latencies by gender, age-group, modality, or side of scalp. Radial current density maps on group-averaged auditory and visual P300 waveforms at the group mean P300 latency at Cz, showed a right centroparietal sink surrounded by sources. This suggests a major right centroparietal P300 generator. Except for the change in P300 amplitudes with age, and the direction of the change in P300 latencies with age, these data on adults are similar to our previous description of P300 topography in normal children. Description of the normal topography of the P300, and demonstration of the lack of topographic differences by gender, age group, modality, or side of scalp, may facilitate the meaningful examination of P300 topography in cognitive disorders. Such an examination might lead to better diagnostic tools and more appropriate treatment of cognitive disorders in adults.