Vocabulary teaching and learning has always been a difficult task for both language teachers and learners since every language learner needs to learn a large number of words for successful communication in the target language. To alleviate the vocabulary learning process, teachers and researchers are looking for new vocabulary learning strategies not only to teach vocabulary easily but also to enhance language learners' vocabulary knowledge as well. Audio-visual materials, as an incidental vocabulary learning strategy, seem to be beneficial in second/foreign language classrooms. The current literature review focuses on audio-visual materials and their effects on vocabulary learning by reviewing the most recent research studies carried out to investigate the effects of this strategy on the enhancement of vocabulary knowledge of the second/foreign language learners. To do this, three 2018 research studies from different international, peer-reviewed journals--Computer Assisted Language Learning, Language Learning & Technology, and Studies in Second Language Acquisition - were selected and discussed. The results of this literature review highlighted the positive effects of implementing audio-visual materials on vocabulary learning. The results also showed that audio-visual materials can help language learners to improve their vocabulary knowledge of the target language. The vocabulary knowledge of the second/foreign language learner can be enhanced incidentally through watching videos and hearing words in meaningful contexts and communication. A brief summary of each research study as well as some guidelines for future research were provided.