Research background: Ethical conduct is considered a pillar of strength within the context of corporate social responsibility. The basic tool for achieving this is a code of ethics, which should form the basis for the ethical management of any company. Globalisation and internationalisation have brought with them the need to have a high-quality code of ethics in place, one that is balanced in terms of content. Purpose of the article: The aim of the research presented in this contribution is to determine, by means of qualitative comparative analysis, to what extent codes of ethics meet key preconditions for efficacy. Methods: The analysis was carried out on a sample set of 40 companies from various industrial sectors, and of various size, ownership structure and origin. All the companies were active in the Czech Republic at the time. The main preconditions for determining the efficacy of a code of ethics, and which therefore formed the basis for the qualitative comparative analysis, were set in advance. Findings & Value added: The results of the analysis revealed that significant differences exist between companies with national and international spheres of activity with regards to the content and form of their codes of ethics. As a consequence, the preconditions for efficacy were judged not to have been fully met. The primary reason for the differences was the level of importance managements and owners of companies assign to a code of ethics and the emphasis they place on adherence to the provisions set forth in them.