Doctoral thesis deals with the relationship between audit and governance structures in credit institutions. After the presentation of previous research regarding the relationship between internal and external auditors and governance structures, credit institutions, company’s governance structures, models of corporate governance and corporate governance mechanisms are elaborated in detail in this doctoral thesis. Special emphasis was directed to the research of internal and external audit, corporate governance mechanisms as well as the relationship between internal and external auditors and governance structures. Furthermore, the communication model between internal and external auditors and governance structures was created, with the goal of contributing to more efficient work of internal and external audit, on the one side, and the work of governance structures of the credit institution, on the other. In order to test the developed hypothesis, quantitative research was conducted within this doctoral thesis. As an instrument of the quantitative research, four questionnaires were used, and aimed at internal auditors, external auditors, members of the management and supervisory board of credit institutions, and bankruptcy managers and professional staff of credit institutions in bankruptcy in the Republic of Croatia. The collected quantitative data were analyzed with different statistical methods. Afterwards, the research results were interpreted as well as implications of the conducted research on the work efficiency of internal auditors, external auditors and governance structures in credit institutions. Based on the conducted quantitative research and taking into consideration that all hypotheses have been confirmed, it can be concluded that the created communication model between internal and external auditors and the governance structures of credit institutions contributes to more efficient work of internal and external audit, and the work of governance structures in credit institutions. Doctoral thesis comprises of the following six main parts: 1. IntroductionVII 2. Presentation of previous research regarding relationship between the audit and company’s governance structures 3. Theoretical background of credit institutions 4. Theoretical framework of corporate governance 5. Audit as a corporate governance mechanism 6. Description of research and research results regarding relationship between the audit and governance structures of credit institutions 7. Discussion 8. Conclusion.