This dissertation discusses the Portuguese - Persian - Ottoman conflict to control the island of Hormuz during the period between 1507- 1622. The research is mainly based on historical archives, printed sources and historical and political references, which are useful for the search, The researcher divided the study in four chapters. The introduction highlighted a brief history of old Hormuz since the fifth century, which is considered as a historical extension of the second Hormuz. It also went through it in terms of the importance of its strategic location, its kings, its inhabitants, its development and its expansion in the Gulf, as well as its political situation before the Portuguese invasion. The first chapter explored the Portuguese access to the eastern world and their campaigns to take over Hormuz Island. It focused on several areas such as the geographical discoveries and their results, the Portuguese access to the Arabian Gulf and the causes of targeting Hormuz. Finally, it underscored the three military campaigns that led to the fall of Hormuz; besides, the Portuguese ruling system and its impact on its social, political and economic aspects. The second chapter shed the lights on different topics that are related to Hormuz Island and Persia. First the Persian reaction towards the Portuguese invasion. Second, the political situation of the Persians in that period and their responses towards the Portuguese campaigns and the Gulf revolutions, where Hormuz Island played an active role in it. The third chapter discussed the presence of the Ottoman to the waters of the Gulf. It started with explaining the reasons behind the absence of the Ottoman navy from the great geographical discoveries in Europe and the reasons behind them heading towards the Gulf after entry the Portuguese in the region. It also discusses the Ottoman political relations with the forces in the Muslim East and the Ottoman's opening of Baghdad and Basra along with the reactions of the civilians in the region. Moreover, it went through their failure to take over Hormuz, their struggle to finally exit from the waters of the Gulf and the impact of the situation on Hormuz. The fourth chapter focused on the liberation of Hormuz in 1622 which happened as a result of the Persian and English alliance, which was supported by the good diplomatic and commercial relations between the two parties in addition to a number of vulnerable factors which permeated the Portuguese. This chapter ended up listing the Portuguese's attempts to restore Hormuz. The study concluded with significant results which are the conflict on the island of Hormuz caused by the importance of its strategic location and its trade which connect the Eastern and Western world. The study highlighted the permanent keenness of the Persians since the Portuguese invasion of to achieve their interests regardless anything alse. This was obvious in two things. First, their reactions to the fall of the island where they were attempting to be an alliance to the Portuguese against the Ottoman Empire. Second, their collaboration with the English against the Portuguese. The study confirmed that the hostile political relations between the major Islamic forces Mamluk, Ottoman and Persian was the main reason that left the door opened for the colonizers to enter the area and control its ports. The study also showed the importance of the national spirit among the population of the Hormuz Kingdom to destabilize the Portuguese. It also clarified that the English were keen to have a strong diplomatic relations with the Persians in the region in order to stabilize their business and compete with the Portuguese. Finally, it underlined the vulnerability factors that led to the domain of the Anglo-Persian alliance, which led to the liberation of Hormuz in 1622.