In the information units that make up the Instituto Mexicano del Seguro Social (IMSS) Library System, the task of guiding and training users on the use of information is a complex process, due to the specificity of the users' information needs. The information systems that are used in the Institute require the personal librarian to have specific information skills for access, evaluation, organization and use of information through information technologies. However, there are important challenges, such as the lack of definition of the professional profile of the medical librarian, because it is essential for the staff to efficiently satisfy the demands and needs of users according to their various profiles.