The present research was an attempt to evaluate the effectiveness of an adaptive online reading instruction with real-time feedback on the reading fluency of Iranian EFL learners and the perceptions of Iranian EFL students and teachers towards the use of the system. To this end, 60 out of 147 Iranian EFL students were selected based and a placement test, and equally divided into equal experimental and control groups. Before the instruction, a reading pretest was administered. The experimental group received instruction using adaptive online reading instruction. The system gave each participant unique reading tasks based on what they needed and how well they could read. There were timed reading tasks, comprehension quizzes, pronunciation drills, and other interactive activities in Hi-ELINA that helped with reading fluency. The instruction lasted for ten sessions. In contrast, the control group was taught through conventional reading instruction. Finally, a reading post-test was conducted. The data were analyzed based on an independent-sample t-test to compare the performance of the pretest and post-test. The findings revealed that there was a significant difference in the reading fluency scores of the experimental and control groups, verifying the efficiency of the adaptive online reading instruction with real-time feedback on reading fluency. In addition, the qualitative findings indicated that both Iranian EFL learners and teachers argued that the adaptive online reading instruction system was well-received by participants and that the real-time feedback provided was effective in improving their reading fluency. Manuscript profile