This article presents fundamental issues concerning the description of the security system of an organization understood as an entirety composed of people equipped with tools, machines and materials, which are connected with one another by a specific bond and between which there are relations connected to ensuring an undisturbed existence and creating opportunities for development. The description of security systems is a complex undertaking. It is a consequence of its complexity, which is primarily a result of the set of relations between organizational elements. They include: accumulation (expressed in the number of hierarchical levels, range (related to the number of subordinations and dependencies), spread (associated with the number of elements subordinate to a single superior at each organizational level), organizational cohesiveness (connected to the mutual structural and functional dependencies between organizational elements due to performed tasks), information links (reflecting the channels and network of information flow), as well as the division of powers (associated with the right to make decisions), and division of duties (related to the relationship between organizational elements). The complexity of the description of security systems is also determined by the activity of the organization’s security systems, which can be divided into: material (concerning the types of activities), temporal (related to the order of its conduct in a specific time), and spatial (connected to conducting activities in specific places). The description of security systems is only possible through the use of: appropriate methodological procedures and a systemic approach, as characterized within the constraints resulting from the expression formula. This paper also indirectly addresses the determinants of the description of security systems. These are: up-to-date knowledge, concreteness and reliability of the description and sufficient detail.