The current study examined five- and seven-year-old Mandarin-speaking children's processing of lexical tones in relation to speech segments by varying onset and rime in an oddity task (onset±rime±). Results showed that children experienced more difficulty in lexical tone oddity judgment when rimes differed across monosyllables (e.g. onset+rime-) than when onsets differed (e.g. onset-rime+). This finding suggests that vowels interfere more than consonants in lexical tone processing. Seven-year-olds consistently outperformed five-year-olds, suggesting that the growth of metalinguistic awareness and literacy exposure may play a joint role in the development of lexical tone processing skills.