This study aims to investigate the effectiveness of using visual materials in teaching vocabulary to deaf students of EFL. For this purpose, 80 deaf students from a state special education vocational high school in Turkey contributed to this study. All students had first English classes in their lives and they are at the starter level of English, thus pre-test for their English proficiency was not given. The students were randomly divided into two groups to form the experimental group and the control group. 10 vocabulary items per week were taught to the students, and 50 target vocabulary items in total were taught during the whole study. To the experimental group, the vocabulary items were taught via visual materials together with the sign language. The control group was not presented with any visual items during the teaching process of the experiment, only sign language instruction was used for them. After the treatment, a vocabulary test was given to each group as an immediate post-test to measure the impact on learning. Six weeks after the immediate tests, delayed post-test was given to the groups to test long term retention. The results of the two post-tests were analyzed through Independent Samples t-test and Paired Samples t-test calculations to investigate the effectiveness of visual materials. According to the results of the study, visual materials were found to be more effective than using only the sign language that does not contain any visual items in teaching vocabulary items to deaf learners who learn English as a foreign language.