Ethics plays a crucial role in today's business world, shaping the relationships between companies, consumers, and society as a whole. In an era where consumers are increasingly informed and value transparency, adhering to ethical standards has become essential for maintaining trust and customer loyalty. This thesis explores the importance of ethics in marketing, highlighting how the application of ethical principles not only contributes to a company's positive image but also directly impacts its success in the marketplace. The paper focuses on Croatian Telekom as an example of how a large company can integrate ethics into all aspects of its operations. By analyzing their organizational structure, marketing strategies, and customer relations, it demonstrates how ethical codes are implemented and practiced. Croatian Telekom has successfully built a strong image as a socially responsible company, basing its business on trust, responsibility, and transparency, which allows it to maintain a long-term competitive advantage. Additionally, the thesis emphasizes the importance of continually adapting ethical standards and educating employees to ensure that the company remains aligned with changes in the social and business environment. In conclusion, the paper confirms that ethical business practices are not just a moral obligation but a strategic tool that can secure a company's long-term success in an increasingly competitive market environment. The case study method was used in the paper, and an example of successful practice was presented. To demonstrate ethics in marketing at Hrvatski Telekom, secondary data sources available on the official website of Hrvatski Telekom were used.