This study reports the findings of the research conducted on the effects of Interest-Based Language Teaching (IBLT) on Persian students' interest in L2 learning, and their achievement in reading comprehension. With the aim of improving L2 learning in the university level, the study investigated whether selecting instructional materials based on learners' interest areas could impact their interest in language learning. Furthermore, it examined whether selecting instructional materials based on interest would have any influence on learners' performance in L2 reading. It also examined any significant differences between the learners with high and low L2 reading levels in terms of interest. The participants were sixty first-year nursing students in a nursing college. Both questionnaires and tests were employed to collect the data. The collected data were closely examined and analyzed using independent-samples t-test. The results revealed that (1) personalizing the materials could make a significant contribution to the development and enhancement of students' interest level in L2 learning; (2) selecting the instructional materials based on learners' interest areas could improve their performance in L2 reading comprehension; and (3) in using IBLT, there was no significant difference between learners with different levels of reading proficiency in learning the course materials.