The aim of this study was to investigate discourse markers in descriptive compositions of 90 Iranian students who were selected from two universities. Without any instruction, they were given a topic to write a descriptive composition per week for 8 weeks. 598 compositions were collected, and they were analyzed qualitatively and quantitatively by three raters following Fraser's (1999) taxonomy of Discourse Markers. Findings showed that students employed discourse markers with different degrees of occurrence. Elaborative markers were the most frequently used, followed by inferential, contrastive, causative, and topic relating markers. There was a direct and positive relationship between the quality of the compositions and the number of well-functioned discourse markers. Results also revealed statistically significant differences between the use of discourse markers and composition quality in the groups. Graduate students used more discourse markers, and this led to more cohesive texts.