In tonal languages such as Mandarin Chinese, suprasegmental tones are used to signal word meaning besides consonants and vowels. To reveal memory traces for tonal language words, we presented native Mandarin Chinese speakers with a sequence of spoken syllables as standards and disyllables as deviants in a passive oddball paradigm. The second syllable of each disyllable carried critical tonal information that would define the disyllable either as a meaningful word or as a meaningless pseudoword. The words and pseudowords were acoustically and phonologically matched as well as counterbalanced. The auditory event-related potential in response to words was more negatively deflected than that in response to pseudowords. This effect was most prominent 164 ms after the word recognition point. Our study indicates an activation of memory traces for tonal language words.