With the growing globalization of the world economy, relationships between importers and their foreign suppliers are becoming closer. However, the international business environment provides a fertile ground for the growth of unethical behavior. This article sheds light on the drivers of the unethical marketing behavior of foreign suppliers, as these are seen from the perspective of their import buyers, and how this in turn affects the quality of their working relationship and the performance that results from it. Based on a sample of 189 importers located in Cyprus, the study revealed that cultural, corporate, and personal values negatively affect unethical marketing practices, which, in turn, negatively influence relationship quality (as this is expressed in terms of cooperation, communication, trust, and commitment). This will subsequently have harmful effects on the performance of the working relationship. The findings of the study have important implications for import managers in terms of properly selecting and handling relationships with their foreign suppliers.