English is learned as a foreign language (EFL) in Iran, but because of the limited opportunities to practice or use it in an everyday life environment, it is not easy to make any distinguishable improvement unless the learners are very interested and active ones. When learning in this kind of EFL environment, students are very likely to experience a certain level of language anxiety, which have some damaging effect on language learning acquisition (Chen & Chang, 2004). As such studies about learners' language anxiety are very important not only in improving learners' language proficiency, but also in achieving a targeted syllabus objective or a particular teaching goal. This study aimed to explore the effect of peer feedback on the learners' classroom anxiety specifically focused on speaking ability. To this end, having administered a test of homogeneity among 70 upper-intermediate EFL male students, the researchers finally selected 50 students who were at the same level of English proficiency and were assigned to two groups- the experimental and the control group- each consisting of 25 participants. For collecting the required data, one homogenizing test, one questionnaire, a semi-structured interview and an opinion test were employed in the study. Having done analysis, the results revealed that peer feedback as a technique, has a significant effect on reducing students' anxiety. The qualitative data from the interview also revealed that the students took benefits from the peer feedback process and enjoyed the course.