Abstract. The aim of the present study was to examine the effect of raising awareness about rhetoric transfer on the ability of writing argumentative essays of Iranian EFL learners. One of the most important issues in EFL mainstream has been the effect of L1 on L2. In discussion of Error analysis, one of the errors with high frequency in the EFL classroom is caused by the interference of first language. It seems that making comparison between L1 and L2 rhetoric can reveal the patterns of negative cultural transfer in writings of EFL learners. The study was conducted with 30 female students of university who were supposed to take task 2 of IELTS writing sub-test. At first all students were asked to take a pretest in which they were required to write a composition about a controversial topic.This test intended to ascertain whether or not students have already gained the ability and techniques to compose argumentative essays. Within the next two weeks, they were taught how to write an argument kind of essay by an experienced IELTS teacher and then they took An IELTS Writing sub-test. The further step included teaching and negotiating contrastive rhetoric of Persian and English to students. After that, the subjects took the similar test. Their writings were analyzed in terms of cohesion and coherence which is one of four criteria that are employed in assessing IELTS writing test. The results of the present study indicated that there is a relation between raising awareness of rhetoric transfer from L1 to L2 and increasing the ability of writing argumentative essay of Iranian EFL writings.