In recent years a number of political, natural, economic, social and technological factors have contributed to the discussion about the security of supplies of crude oil and its products. There are many questions as to how a logistic security system of supply should be built to meet the requirements for effectiveness, efficiency, flexibility and continuity. Although the subject is so often discussed, it still seems to be not quite understandable and clear. This paper is an attempt to refer to this issue through a theoretical analysis of the concept and structure of the logistic security system of liquid fuels supply. The first part of the paper presents the issues pertaining to a logistic system approach, which is the starting point for a further discussion. In the second part are the basic conditions for the functioning of the crude oil market. Additionally, the subject revolves around the interpretation of the energy security term and its fundamental components. In turn, the third part leads to the identification of elements and structure of the logistic system of liquid fuels. The paper ends with considerations about the usefulness of the results for further research on the logistic security system of supplies of crude oil and its products.