Financial literacy, i.e. the ability to make correct financial decisions, is the basis for successful management of individuals' personal finances. The increasing representation of research on the topic of financial literacy has become imperative due to the rapid development of the financial market and significant demographic changes. In today's increasingly demanding economic environment, financial education has proven to be essential for understanding the complexity of financial products and services. This thesis examines the impact of opportunity cost on the financial planning of young people in the Republic of Croatia. Young people face numerous challenges in their financial decisions, and understanding opportunity costs can significantly facilitate their financial decision-making. Given the dynamic environment and changing economic conditions, research into the impact of opportunity costs on the financial planning of young people becomes essential for the timely recognition of the needs and challenges they face. The survey was conducted among students throughout the Republic of Croatia. The questions in the survey cover aspects of financial planning, the perception of opportunity costs and the method of financial planning, the level of financial literacy as well as the general financial habits of young people. The main focus of this paper is to examine how the concept of opportunity cost affects student’s financial decision-making. The research results showed that students in the Republic of Croatia generally do not have a detailed financial plan, even though they have financial goals. Furthermore, economics students consider options better and are more willing to make greater sacrifices for saving, thanks to better financial education and understanding of the concept of opportunity cost.