The purpose of this study, or rather the overall study of the role of internal audit in credit institutions s to determine the importance and role of the function of internal audit in detecting and preventing fraud in credit institutions. Empirical research was conducted using two types of anonymous survey questionnaires, one of which is intended for internal auditors in credit institutions, and the other for users of internal audit findings in credit institutions. They were conducted with the aim of gaining knowledge about the importance of the internal audit function for detecting fraud, its organizational position within the credit institution, the importance of cooperation between management and internal auditors and the need for education and regular training of internal auditors. Anonymous survey questionnaires were completed by 7 internal auditors and 5 users of internal audit findings, and given the small sample, we can say that the research results are more suggestive than convincing / proving. In accordance with the conducted research, we can conclude that internal audit is independent and objective in its operations, that it has an exceptional importance and contribution to the work of the credit institution and in detecting and preventing fraud that may endanger its operations and survival. Research has shown that it is important for internal auditors to have expert knowledge and experience and to be regularly educated in order to detect and prevent fraud. Respondents of the conducted surveys agreed with the statement that a defined plan of prevention and response to fraud in a credit institution enables efficient limitation and quick response to detected fraud and management of the situation. The only claim that has not been confirmed by testing is that the cooperation of internal audit and management enhances the success of fraud prevention and detection.