Purpose - The purpose of this paper is to investigate the influence of moral philosophy on the ethical beliefs of auditors. The paper argues that an individual's moral philosophy is the key factor in how one views ethical issues and largely determines the ethical choices one makes. The paper also seeks to discover the influence of personal values on the reasoning processes associated with ethics and to explore whether the personal value preferences of auditors, as a manifestation of their moral philosophy, influence their ethical beliefs and (presumably) their subsequent actions. Design/methodology/approach - The authors designed a survey instrument to assess the value preferences, moral philosophies, and reactions of practicing auditors to judgment dilemmas. They then employed structural equation modeling to examine the sensitivity of auditors to the competence and integrity of clients with the aim of gaining insight into the ethical beliefs of auditors in general. Findings - These results show that value preferences alone fail as predictors of ethical beliefs. Instead, personal values have an indirect influence on ethical beliefs via moral philosophy. Moreover, auditors strongly motivated by values based on self-enhancement were negatively associated with idealism in ethics and positively associated with relativism. Therefore, it can be concluded that idealist auditors were more likely to condemn the actions of clients that violated moral norms, while relativist auditors were more permissive. Originality/value - The results identify the role of moral philosophy as a mediator for the personal values and ethical beliefs of auditors, shedding light on how personal values can influence ethical sensitivity.