Purpose - The present study aims to review the literature concerning Digital Libraries (DLs) and user interfaces in order to identify, determine, and suggest evaluation criteria for a DLs user interface. Accordingly, this study's objectives are threefold: explore which criteria exert a significant relationship with the DLs user interface; identify a set of criteria that appears to be useful for evaluating DLs user interface; and determine evaluation criteria that have more frequency and occurrence in the related texts reviewed. Design/methodology/approach - To do it, first, identifying related texts was necessary. Consequently, keywords such as "DLs user interface evaluation"," DLs user interfaces", "DLs evaluation", "DLs usability", "user interface evaluation", "DLs research", "web sites user interface evaluation", "user interface standards", and the like have been searched in the web as well as in some leading databases including Emerald, Proquest, SagePub, ScienceDirect, LISA, ERIC, ACM, and Springer. After identifying and accessing more than 100 evaluative works and some related articles, theoretical and empirical, nearly 50 sources were chosen for final examination. Findings - After reviewing related texts, three major categories are identified: user interface and DLs; DLs and usability; and other studies related to user interface; each one of three identified categories has its own subcategories. Additionally, 22 evaluation criteria for assessing DLs interface have been identified. Research limitations/implications - The review does not claim to be comprehensive. Practical implications - Hopefully, criteria such as feedback, ease of use, match between system and the real world, customization, user support, user workload, interaction, compatibility, visibility of system status, user experience, flexibility, and accessibility which have been less considered should be applied more in future, particularly user-oriented, studies. Furthermore, it is expected that criteria mentioned here could help related bodies pay more attention to the evaluation of EISs, especially DLs interface. Originality/value - It can be said that this study has contributed to the research into the evaluation of DL interface.