Systemic functional linguistics has provided a systematic approach to analyze texts. Different strata of Systemic Functional Grammar have shed light on studies. In this paper, the topic has been restricted to one aspect only, i.e. the textual metafunction, which is realized by the thematic structure. Marked thematic structure is the area of differences between source language and target language which challenge translation process. The present study is the contrastive study of marked thematic structure in English argumentative texts and their Persian translations. It has been benefitted from Shimid's classification of marked thematic structure. The data are extracted from the first 1000 sentences of two English argumentative texts and their translations into Persian. For each kind of marked thematic structure strategies used by translators were identified. It attempts to see what corresponding processes are actually used in Persian translation. The result of the study showed that construction with adjunct fronting posed more challenge for translators than passive sentences or cleft or pseudo-cleft sentences. The results can be useful for everyone who wishes to get familiar with the process of translation, in transferring not only the semantic contents, but also the thematic purports of the source into the target language..