Second language development could be achieved through various teaching or learning processes; however, employing multimedia has recently intruded the process in easing or complicating manners. This study has focused on the effectiveness of English subtitles on the EFL learner's vocabulary learning. The participants were 92 Iranian degree university students studying Translation at Islamic Azad University of Mashhad, Iran. Having set two homogenized groups on the basis of their English language proficiency level, each was randomly assigned to be control and treatment groups. They were given two different instructions, one practicing instructional video episodes with subtitles and the other without subtitles. Their vocabulary learning was tested by a Content Specific Test (CST). The mean scores of the two groups were compared through a t-test. The findings illustrated that participants viewing the videos with subtitles could obtain a significantly higher mean score of the CST vocabulary tests than that of the ones who viewed the videos without subtitles. The findings of this research can get educators well informed of the effectiveness of subtitles on EFL learners' better vocabulary learning. (Contains 4 tables.)