The goal and purpose of this thesis is to explain subprime mortgage loans and their role in the global crisis. The concept of mortgage loans and financial crises in general is explained. Special emphasis is placed on the processing of subprime mortgage loans and their role in the global crisis, as well as their existence in today's world. The paper states the theories and causes of financial crises and the types and role of subprime mortgage loans in the past and present period. Furthermore, the causes of the global financial crisis of 2008. and its impact on the world economy and the real estate market will be analyzed. In this connection, the imbalance in the global real estate market caused by subprime mortgage loans will be analyzed. Namely, the cause of the crisis was marked by a rapid drop in real estate prices that were sold en masse and financial institutions that granted loans in an uncontrolled manner and without additional collateral. Citizens bought real estate thinking that they did not have a big risk because they could always sell the real estate and make money at the same time, since the demand for real estate was on the rise and their price was rising. Banks also considered that the same real estate that they mortgaged when approving the loan would later be sold at a higher market price if the borrower was unable to repay the loan. Of course, the idyllic picture did not last long, and real estate prices began to fall sharply because the real estate market suddenly became saturated and there was no one to buy real estate. Also, the consequences and outcomes of mortgage loans and their role in the crisis will be clarified. Finally, mortgage loans and their role in today's world are presented.