This paper explores the ethical reasoning of internal auditors and examines the impact of other corporate governance mechanisms on their ethical sensitivity and judgments. We also explore whether ethical reasoning is influenced by years of experience in internal auditing. Sixty-five internal auditors were presented with five ethical dilemma scenarios. Five corporate governance variables were manipulated. These were, audit committee support; management integrity as regards accounting policies; management integrity as regards pressure on internal audit; external auditor characteristics; and organisational code of conduct. The results indicate that the characteristics of the external auditors appear to impact internal auditors’ ethical decision making. However, we do not obtain significant results for the other four variables. We also find that years of experience has some influence on ethical reasoning.