This research was conducted in the 8th-grade of a Junior High School in Sawit. The subjects of this research consisted of 17 male students and 14 female students. This research was aimed to improve the students’ reading comprehension in English classes and to find the problems that occur when authentic materials are used in reading class. This research had two cycles, and each cycle consisted of two meetings. The research methodology that was used in this research was classroom action research (CAR). This action research consisted of four steps: planning, acting, observing and reflecting. The data were collected from observation, interview, research diary, and document. The result of the research showed that the students made an improvement in the first indicator of reading comprehension. The average score of the students in the pre-test was 60.9. Then, after using the authentic materials, the students’ average score was improved in the post-test 1 into 66.1, while in the post-test two, their average score was 78.1. Based on the observation result, several problems happened during the implementation of this technique; namely time management, difficulty in finding the main idea, and difficulty in vocabulary mastery.

Keywords: Classroom Action Research, Students’ Reading Comprehension, Authentic Materials.