Due to the importance of decentralization and the development of university based curriculum, most decisions regarding the design, implementation, evaluation, modification, and review of curricula are made by universities. Since delegation of Implementation Circular Curriculum Revision to universities has changed a large part of the curricula, and since any changes may be difficult, the present case study aimed to identify the challenges of implementing revision of curricula. Using purposeful sampling, semi-structured interviews with 10 administrators at various departments of Ferdowsi University of Mashhad were conducted. Based on the findings, the challenges of changing and implementing the curriculum are divided into two general categories of revision of curriculum, and the implementation processes. The challenges of revision process included limited authority of academic departments, inability to predict the possibility of making moderate and minor changes in the curriculum, performing support studies, unclear expectations and lack of curriculum literacy among faculty members. The challenges of implementation process included resistance to change, lack of sufficient motivation to participate in implementation, how to present lessons, shortage of space, time and educational facilities, shortage of human resources, , lack of monitoring mechanism for good implementation, and lack of support for change and implementation.