In order to explore the effects of tone categories on the perception of Mandarin vowels, the present study investigated the perceptual performance of vowel continua, which contained three Mandarin vowels /a, ɤ, u/ under four different tone conditions (i.e. high-level, mid-rising, falling-rising, and high-falling tones). The results showed that there was a shift in the categorical boundaries of /a/-/ɤ/ among the four different tone conditions. More specifically, participants generally tended to label the stimuli less as /a/ under the high-falling tone compared with the other three tone conditions. Moreover, the maximum identification rate of /ɤ/ was much lower under the falling-rising tone in contrast with other tone conditions. These findings suggest that vowel perceptions may be strongly influenced by the pitch properties of different tone categories.