This paper examines the influence of gender upon voice onset time (VOT). VOT values of word-initial stops /p, t, k, ph, th, kh/ followed by three vowels /i, u, a/ in both Mandarin and Hakka revealed that male speakers produced longer VOTs in unaspirated stops than their female counterparts, but women produced longer VOTs in aspirated stops than male counterparts. In addition, VOT distinction in unaspirated and aspirated stops was greater in female speakers than in male speakers in both languages, perhaps because women tend to have a more careful manner of speech than men (Byrd 1992, 1994; Whiteside 1996). Gender has a statistically significant influence on VOTs in both Mandarin and Hakka. It is thus suggested that VOT data from different genders should be analyzed separately.