This work is a literature review that elaborates on the topic of operational risk in financial institutions, its characteristics, measurement, management and underlying regulations. Can proper operational risk management decrease losses in financial institutions? Question that will be the heart of the book and answered accordingly in the conclusion based on secondary sources. In the first two chapters the concept and definition of operational risk will be described following by the third chapter elaborating on the regulatory requirements in the context of operational risk. In the fourth chapter the main tools of operational risk management will be introduced. Finally, in the fifth chapter three cases of operational risk failures were chosen in order to present the importance of problematic explained in preceding chapters.