abstract tasks nowadays are at the center of attention in sla research. task types is one of the critical issues in this regard, their effectiveness and suitability to any particular context, their characteristics and the result they yield are among some of these issues. on the other hand, discourse markers (dms) have been very much investigated and their effectiveness in conveying the meaning is proved. however, literature is poor with regards to the relationship among discourse markers and different tasks types. in this study, the researcher tried to see whether students were likely to use more dms in information-gap tasks or reasoning-gap tasks. moreover, he investigated the effectiveness of input- enhancement type of instruction on students’ acquisition of dms. to this end, students in control and experimental groups were assigned aforementioned types of tasks to negotiate and then to observe the utilization of dms. then in the treatment part, the experimental group was exposed to the visual input enhancement type of instruction to evaluate its efficacy in students’ use of dms. the findings indicated that students utilized equal number of dms in both type of tasks and there is not any significant difference between two types of tasks. furthermore, the statistical analysis showed that input enhancement did not have any effect on students’ acquisition and use of discourse markers. it can be said that iranian efl learners need more exposure to different types of dms and the materiel’s developed for language teaching in iranian context need to provide rich context regarding dms.