Abstract : This thesis means to tackle the issue of amending constitutions in countries that adopt the mixed system, which is difficult and complex in its procedural and substantive aspects. The research consist of an introduction, introductory chapter, and three main chapters. The introductory chapter addresses the core concept of the mixed system, its establishment/ foundation and application in the Kingdom of Bahrain, State of Kuwait, and Arab Republic of Egypt. In addition, the latter part of this chapter, briefly discuss the concept of amending constitutions and its main types. The first chapter addresses the issues related to the first phase of constitutional amendment, which is the proposal to amend the constitution. The chapter clarifies the authorities, which can propose constitutional amendments in the Kingdom of Bahrain, State of Kuwait and the Arab Republic of Egypt. In addition, it tackles the time-limitations and substantive restrictions to this process. The study conclude that the constituent authority in fact cannot limit the power of the authorized bodied to propose constitutional amendments because of the right of subsequent nations to do so if the need arises. The second chapter addresses the issues related to the second phase of constitutional amendment, with is the preparation of the amendment draft, its. discussion by the Parliament. The study concludes that constitutions varied in defining the body authorized to prepare the amendment draft. In addition, it found that there are several legal implications to Parliament's decision on amending the constitution. The third chapter addresses the issues related to the third and last phase of constitutional amendment, with is the implementation of the constitutional amendment. In this regard, the study emphasis the need to subject constitutional amendments to the Judicial Supervision of the constitutional court and lays a number of justifications. In concluding marks, the study reveals the main outcomes of this thesis aligned with core recommendations in order to improve the process constitutional amendments, especially in the Kingdom of Bahrain, State of Kuwait and Arab Republic of Egypt.