This study aimed at examining the probable impact of three distinct approaches to teaching writing, namely Process, Process-product and Product approaches on the rhetorical organization of EFL learners' argumentative essays. To fulfill this aim, after ensuring the homogeneity of the 45 participants of the study through Oxford Placement Test (OPT) the learners who were all at the intermediate level of English proficiency were divided into three groups comprising of 15 learners, each receiving instruction for 6 sessions based on the aforementioned approaches. After teaching the basic structure of an argumentative essay, the students in each group were required to write an essay in each session. In the last session they were asked to produce an essay which was considered as their post-test. The rhetorical organization of their writings was analyzed using a rubric adopted from the study of Tsai (2006). Using SPSS 16, the results of Oneway ANOVA at the alpha level of .05 revealed that there was a significant difference between those who wrote based on process approach and also process-product approach and those who were taught on the basis of product approach to writing. The pedagogical implications of the study are further discussed throughout the paper.