This study aimed to investigate the effectiveness of using authentic materials on ESP students in reading comprehension. The participants of this study were the second semester students. Purposive sampling technique was used in this study. The participants were divided into two groups, the experimental was 30 students and the control group was 30 students. This study used quasi-experimental research. The instrument used in collecting data was multiple choice test. The total items of the test were 20 items. The finding shows that a mean score of 29.87 on the pre-test and 52.07 on the post-test reading through authentic materials can help students become more proficient readers, particularly in areas such as identifying primary ideas, supporting details, factual interactions, topic-related vocabulary, pronouncing references, and word meaning recognition. It shows that the hypothesis alternative (ha) was accepted. As conclusion that using authentic materials has positive effect of the students’ reading comprehension of English for specific purposes (ESP) class at UKI Paulus Makassar.