The purpose of this study is to examine the approaches by human resource management units in utilizing personnel regulations on preventing unethical behaviors and encouraging ethical behavior. HRM includes effective management of individuals in order to realize organizational objectives. The human resources managers may encourage ethical behaviors within an organization by their increased participation in the ethical initiatives of the organization. Unethical behaviors, in addition to being associated with the personal characteristics of the individuals working in the organization, may as well arise from the organization itself. Unethical conduct includes behaviors that lead to damaging consequences for the others, through disregarding the laws, policies, regulations and organizational norms, which define the broad legal parameters for the sustenance of the society, and are considered as illegal or unethical by the society. To that end, the personnel regulation of a leading enterprise in Turkey has been analyzed through the contents analysis method. The analysis performed over defined codes (themes) demonstrates that enterprises may effectively benefit from personnel regulations in developing an ethical working environment. As a result of the study, it has been observed that there are many articles in the enterprise's personnel regulation aimed to prevent unethical behaviors. At the same time, it has been noticed that there is a separate section titled "principles of business ethics" aimed to direct and support ethical behaviors and that the articles in the other sections of the regulation are in support of these principles.