The aim of the present study is to investigate the effect of metatalk activity on Iranian Advanced EFL Learners' knowledge of passive tenses. 60 advanced level institute learners, who participated in this study, were randomly selected via a language proficiency test (TOEFL). Those who got ±1SD in the test were chosen. They were randomly assigned into two experimental and control groups with 20 participants in every group. An English grammar test related to the usage of passive tenses was administered to both groups in the pre and post-tests. Treatment sessions lasted for 8 sessions but with different methodologies. Teacher in both groups explained about different passive tenses in every treatment sessions. However, learners in the experimental group were treated with metatalk activity and they tried to complete exercises collaboratively with their peers and teachers. They have to complete a dictogloss task with the help of their peers due to focus on learning passive verb tenses. While the control group did not received dictogloss as a metatalk activity and completed the exercises at home and the next session checked the answers. A posttest of grammar was then administered to both groups. The data of the study were analyzed using the independent samples t-test to compare the means of grammar knowledge in both groups. The results revealed that Iranian EFL learners in the experimental group received higher score in the grammar test after being treated with metatalk activity for 8 sessions. It can be conclude that metatalk is an effective method for teaching grammatical knowledge and teachers can use it in their classes.