This research deals with the concept of performance measurement, evaluation, standards and its application in university libraries for the first time. The results of this research will benefit library specialists, staff and administrators who wish to develop library services and resources that focus on users and contribute to improving the performance of staff. This research used the descriptive analytical method, field study and questionnaire, two samples were chosen to be studied applying stratified random sampling which are lecturers and students at the Lebanese University: Faculty of General Medicine, Faculty of Dentistry and Faculty of Pharmacy. Therefore, 184 forms were sent via emails and hatsapp to lecturers, only 11 responded which makes this sample of no use to study. As for students, 306 forms were distributed, and 213 were retrieved, which is equivalent to 69.6% of the total number of forms. Only 130 of it (61%) responded to the questions, while the remaining (39%) did not visit the library at all. The research questions included: available facilities and tools, library collection, quality and satisfaction of services, frequency and use of the library, staff effectiveness and skills and the extent of their cooperation with students… The research results showed the big difference between expected performance and actual performance, which was manifested by the weakness of the library collection and services in the library. It demonstrated users’ needs to extend working hours, provide and improve facilities and enhance information technology. After collecting information and analyzing the results, the standard ISO 11620-2014 was applied after selecting several valid indicators to be used in the library of medical sciences which confirmed the opinions of the users regarding the weakness of the services provided. In an effort to reconcile the expectations and needs of the users, the research concludes several suggestions from the students’ responses and comments, including: increasing working hours, remote access to electronic resources, improvements in technology, increasing the number of staff and training them, and increasing facilities and tools. The research also recommended to adopt the culture of assessment for academic libraries and to development strategies to measure the quality of services and information resources and evaluate it to reach the stage of determining the effectiveness of the library from the perspective of the user. In other words, evaluation studies should be conducted and directed to focus on the user when evaluating information services, as well as participating in the development or/and adoption of specialized standards. All this cannot be done without the concerned department as it is the decision maker in all matters regarding the library.