Sight translation is the oral translation of a written text and is a mixture of translation and interpreting. Sight translation is a widely-used activity in translation training programs. Yet, this mode of translation has rarely been applied as a reading instruction technique in Iranian EFL instruction context in spite of the growing interest in using sight translation in language teaching and learning. This study aims at investigating the effect of sight translation on the reading comprehension ability of Iranian undergraduate EFL students. This is a quasi-experimental study involving treatment. To this end, four reading comprehension classes involving 70 learners were divided into two groups, with the experimental one receiving reading instruction with sight translation exercises and the control group receiving reading instruction without sight translation exercises. The posttest results revealed that the experimental group performing sight translation exercises in classroom outperformed the control group who had not engaged in sight translation. This study has implications for ELT instructors and learners in an Iranian context as they can use sight translation exercises as an effective technique for improving the reading comprehension ability of their learners.