The aim of this study is to find out the effects of peer feedback on EFL students' written performances in essay writing. For this end, this experimental study was conducted with a group of students (n=8) studying at the English preparatory school of a state university in Turkey during the 2017-2018 academic year. Students received feedback from their peers for the four different essay tasks for which they produced a first draft and a second draft during the course of eight weeks. Students were also administered a written pre-test and post-test. The number of correct revisions in second drafts was calculated by using Conrad and Goldstein's (1999) taxonomy. The quantitative data coming from pre-test and post-test were analysed statistically with SPSS by conducting paired samples t-test. The results showed that peer feedback helped students write 69% of the feedback points provided by their peers correctly. Also, the written test results indicated a statistically significant difference between the pre-test and the post-test. In the light of these findings, it can be concluded that peer feedback can be an effective tool in improving students' correct revisions in second drafts and it may help EFL learners perform better in a written post-test