The N400 event-related potential (ERP) is a brain response to any potentially meaningful stimulus. Like reaction time (RT), the amplitude of this ERP is reduced by the prior presentation of a semantically related stimulus. However, results of a few studies suggest that this semantic matching effect could be reduced when using already presented stimuli, and rapidly disappear with further presentations. On the other hand, the topography of the N400 on the scalp depends on the semantic category of the stimulus. Like the semantic matching effect, this category effect also seems to be smaller for already presented stimuli. Taken together, these facts suggest that the semantic processes indexed by the N400 could be absent for stimuli that have already been presented multiple times. Here, we show that this conclusion would be premature. We used the same semantic categorization task in conditions of massive repetition and in conditions of single presentation. We found that the effects of semantic matching and of semantic category on RTs and N400s were similar in the two conditions. Moreover, the localization of the sources of the independent components accounting for the match effect revealed brain regions that were common to both conditions. These results suggest that N400s and RTs could be used to study the semantic processes triggered by one content word.