The present study examined whether written syllable units are perceived in first steps of letter string processing. An illusory conjunction experiment was conducted while event-related potentials were recorded. Colored pseudowords were presented such that there was a match or mismatch between the syllable boundaries and the color boundaries. The results showed that congruent stimuli for which the syllable and color boundaries coincided produced a greater positive-going waveform than incongruent stimuli for which the syllable and color boundaries did not coincide. This syllable-color congruency effect was observed to occur both prior to 100 ms, and in a time window commencing at 150 ms. This finding suggests that syllable units are perceived in the initial steps of French visual word processing. Moreover, this study underlines the specificity of the illusory conjunction paradigm as a relevant and powerful tool of investigation of sublexical units that are automatically evoked from word perception. (Contains 2 figures.)