Behavioural studies have suggested that lexical access is relatively unaffected by normal aging unlike other aspects of semantic processing. This psychophysiological study was designed to gather further evidence on the issue. Using an oddball procedure, an auditory N400 was recorded in both young (mean age 27.7 years) and elderly (mean age 65.1 years) volunteers in normal health. The target was either a high frequency word or a non-word, in two different sessions. The amplitude, onset latency and duration of the N400 did not differ in the two groups of subjects although the peak latency was delayed in the elderly group. The earlier N100-P200 complex had also a longer duration in the elderly group. The results indicate that aging processes affect the various stages of perceptual processing and language comprehension in different ways. Whereas P200, the main index of perceptual processing, was slowed, some measures of lexical access were found to be stable with age.