Whistleblowing is one tool, among many others, to prevent, deter and detect violations of the law or of the firm’s own ethical norms. This article presents proposals to set up an effective internal whistleblowing platform within a firm. These proposals outline the procedures that should be followed to handle whistleblowing reports. In addition, the article explains how an internal department or an externalized service should be set up to process these reports. The purpose of these proposals is to reach a satisfactory compromise between the interests of the firm in having its own values upheld, the interests of the State in securing compliance with the laws, the interests of the employees in working in an honest and safe environment, the interests of other stakeholders to be treated fairly and finally, the interests of denounced parties not to be wrongly accused.