Research has indicated that writing argumentative essay is difficult for L2 students of English, as such the current project intended to examine the difficulties which Iranian EFL students have in writing argumentative essays and also to investigate similarities and/or differences in the way they structure their English and Persian argumentative essay before and after instruction. This study also attempted to portray how students transfer rhetorical patterns in L2 to L1 compositions. This study shed further light into the impact of explicit and implicit genre-based approach in comparison with the no-instruction approach on the argumentative genre. After conducting TOFEL test, 79 subjects were selected. The selected subjects were randomly divided into three groups. All of the three groups did 4 pre- and post-tests. The results show that the participants used basic structure of English argumentative papers in both their Persian and English pre-essays; however, they were weak at handling oppositional structures. The quantitative analysis of the post-argumentative essays revealed that the experimental group outperformed the implicit and no-formal instruction groups.