An auditory "oddball" paradigm was used to elicit the P300 component of the event-related brain potential (ERP) from a large sample of young (5 to 15 years) and older (20 to 86 years) persons. Distinct P3a and P3b subcomponents of the P300 were observed within individuals and across trial blocks. Age affected P300 latency in a similar fashion for both subcomponents with latency increasing about 65 msec between 20 and 70 years. P300 latency variability also was found to increase somewhat with advanced age. These results confirmed previous age-related ERP changes and extended them to the P3a and P3b subcomponents.