Millions of dollars have been invested into the development of digital libraries. There are many unanswered questions regarding their evaluation, in particular, from users’ perspectives. This study intends to investigate users’ use, their criteria and their evaluation of the two selected digital libraries. Nineteen subjects were recruited to participate in the study. They were instructed to keep a diary for their use of the two digital libraries, rate the importance of digital library evaluation criteria, and evaluate the two digital libraries by applying their perceived important criteria. The results show patterns of users’ use of digital libraries, their perceived important evaluation criteria, and the positive and negative aspects of digital libraries. Finally, the relationships between perceived importance of digital library evaluation criteria and actual evaluation of digital libraries and the relationships between use of digital libraries and evaluation of digital libraries as well as users’ preference, experience and knowledge structure on digital library evaluation are further discussed.