This article explores the consequences of the anti-colonial politics inIran, which Mohammad Mosaddegh led in the 40-50s of the 20th century. Throughout adopting the biographical method, we have studied the core aspects of Mosaddegh’s worldview, which laid the foundation for different approaches to Iranian nationalism. “Mosaddeghism” and “Mosaddegh Syndrome” was founded on sharply expressed anti-colonial nationalism and soon became the driving force for the so-called third-world countries, creating a new geopolitical reality in the Middle East region. As a result of the research of the secondary sources and the historical context, we have introduced the trends and consequences of the geopolitical transformation following the nationalization of the Iranian oil company.