This investigation explored the voice onset time (VOT) values of word-initial bilabial stops /p/ and /b/ as realized by Arabic-speaking male and female Saudi ESL learners. It sought to identify the differences, if any, between these two groups with regard to this acoustic measure (i.e., VOT). The VOT measurements were then compared with those of native English speakers to test the contrastive analysis (CA) hypothesis. The VOTs were measured from the recordings of the 20 participants (10 females and 10 males). This study used the Praat speech analysis software to measure VOT values. The results revealed a statistically significant difference between male and female participants in their VOT values for /b/. For the VOT values of /p/, no statistical difference was found in the results. Further, an increase was detected in the male participants' VOTs for /b/ compared with those of native English speakers. The remainder of the results were relatively in line with the VOT values of native English speakers; namely, both males and females acquired the voiceless phoneme /p/ despite the lack of this phoneme in their native language (Arabic).