Funds from the EU budget finance numerous development projects with the aim of improving the lives of all EU citizens. Improper use of them directly harms citizens and the entire European project. The European Anti-Fraud Office, OLAF, is the only EU-level body in charge of detecting, investigating and combating fraud with funds from the Union budget. The paper presents the expediency and historical development of the office, the achieved results and guidelines for the future based on detailed analyses. To get the best possible picture of the work of the office, detailed annual reports of OLAF for the five-year period from 2016-2020 were used. years. The forensic investigations carried out are clearly presented through numerous examples from practice, as well as the financial results achieved by these investigations. At the end of the work, attention was paid to the compatibility of the legal regulations of OLAF and the national legislation of the Republic of Croatia. Numerous scientific methods were used in the work, such as analysis, synthesis, deduction, statistics, etc. Based on the research, the obtained detailed data listed in numerous tables lead to the conclusion that the establishment of a body like OLAF is a praiseworthy and above all effective EU project that really protects the financial interests of the entire Union. It is up to the national legislation to adjust the legal regulations and methods of financing the competent services for better and more efficient cooperation with OLAF, all with the aim of better financial results both in the Republic of Croatia and on the territory of the entire EU.