The voice onset time (VOT) of stop consonant is defined as the time interval between the release of a stop and the onset of the following vowel (Lisker and Abramson, 1964, 1970). Previous studies indicated that VOT could be used as a perceptual cue for identification of both voicing and place of articulation of stops (Kewley-Port, 1983; Ladefoged, 2001). Abramson (1977) suggested VOT could be interpreted as interrelated acoustic consequences of variation in the relative timing of glottal and oral gestures. This study will attempt to extend the probe on this suggestion by comparing the VOT values among different tones. Mandarin, which is a tone language, where a change in the tone of a syllable leads to a change in meaning, will be used in the study. There are four contrastive tones in Mandarin, each of which is realized by changing the vocal pitch during the course of the syllable production. The proposed study will determine if VOT values for each of the six stop sounds (/p,b,t,d,k,g/) will vary with the variation of different tones at which each of the following vowel sounds is produced. The interrelationship between VOT and tone production will be discussed.