APA Citation: Yazdfazeli, M. Motallebzadeh, K., Fatemi, M. A. (2015). Explicit back-channel strategy training and improvement of speaking skill: case of Iranian EFL learners. Doff (1990) and Harmer (1991), post-test oral proficiency test was administered for experimental and control groups. The findings of pretest and posttest oral exams revealed that EFL language learners' oral performance (speaking) in experimental groups improved. The result revealed that females employed back-channels more often than males when they were participating in a conversation. The type of back-channel both genders employed the most was short utterances, such as 'yes', and the most used function of back-channel was request for clarification. The results of this thesis will provide language teachers, EFL language learners, researchers, material developers, and readers, useful information about the types and functions of back channels that are needed to develop speaking ability appropriately through explicit teaching.