Purpose: University libraries are increasing their e-book collections. The purpose of this study is to investigate graduate students' usage of and attitudes towards e-books at National Taiwan University. Design/methodology/approach: A total of 20 graduate students from the fields of humanities, social sciences, science and technology, and medicine were interviewed. Findings: The results indicated that graduate students used e-books mainly for the purposes of study and research. Monographs were the type of e-book that students used most often, followed by textbooks and reference tools. While they appreciated the convenience of using e-books, students mentioned several limitations. They liked the keyword search function of e-books. Most of the time, graduate students browsed a few paragraphs or pages online and then printed out copies for further reading. They also borrowed the corresponding paper versions of the e-books from the library. Students preferred that university libraries supply both the electronic and paper versions. In certain aspects, students' use behaviour was found to vary among disciplines. Originality/value: This study highlights multiple aspects of graduate students' use behaviour with respect to e-books. The findings could be used to enhance e-book collection development in university libraries. (Contains 4 tables and 1 figure.)