Interactive multimedia e-books are becoming increasingly popular in schools, but their effect on lower-secondary school students' curiosity in a science course is unclear. Curiosity is a form of intrinsic motivation that plays an important role in student success in school. This study examined the effect of using interactive multimedia e-books on lower-secondary school students' curiosity in a science course. A quasi-experimental design was employed. A total of 64 students (12 to 14 years old) in a state lower-secondary in the city of Yogyakarta, Indonesia, are used as experimental (n = 32) and control (n = 32) groups. The subjects were taught by their regular science teachers that served as an assistant in the research. Both groups (experimental and control) were pre-and post-tested. The experimental group used interactive multimedia e-books, while the control group used printed textbooks. The student curiosity questionnaire is given before and after the treatment. Curiosity observations are made during the treatment. Independent and paired sample t-test was used to test the hypothesis at a significance level of 0.05 (data from the questionnaire). Quantitative descriptive is used to analyze observational data. The results of the independent sample t-test showed that there was a significant difference in student curiosity between students who used interactive multimedia e-books and students who used printed textbooks. The results of the paired sample t-test showed that there was a significant increase in students' curiosity in science courses after using interactive multimedia e-books. Meanwhile, students who used printed textbooks did not experience a significant increase in curiosity. The results of the questionnaire were also supported by the results of observations which showed that the curiosity of students in the experimental group was higher in percentage than in the control group.