the aim of the present study was to investigate the frequency and the type of discourse markers used in the argumentative and expository writings of iranian efl learners and the differences between these text features in the two essay genres. the study also aimed at examining the influence of the use of discourse markers on the participants’ writing quality. to this end the discourse markers used in two essays (an argumentative and an expository) written by the participants of the study were analyzed. the results indicated a hierarchy of use of discourse markers in both essay types with elaborative markers (mainly “and”) the most frequently connectors used in both essay types. next came contrastive and inferential markers; reason, exemplifier, and conclusive markers, respectively, were the least frequently used connectors. the results, moreover, indicated that, on the whole, the mean of discourse marker use was significantly higher in argumentative essays than in expository essays. as for the individual categories, contrastive and conclusive markers were used more frequently in argumentative than in expository essays. the results, nonetheless, showed that the use of discourse markers cannot be a significant predictor of the writing quality in argumentative and expository compositions of iranian undergraduate efl students.