Development of the system theory and its influence on logistics resulted in common usage of formal recording of logistics processes in a form of a logistics model. The presentation of the entire logistics activity in a form of a system yields benefits consisting in the possibility of defining close relations between selected subsystems, which makes it possible to conduct in-depth studies as regard efficiency. The basis for considering efficiency of logistics systems is adoption of a correct model to be subsequently analysed. This model reflects actual processes to be analysed within a given logistics system. A correct mathematical recoding method for a logistics system is of key importance for efficiency measurements. It must take into account all dependencies, limits and boundary conditions connected with the specificity of the system studied. The least complex case in the logistics system theory is a system encompassing relations between one provider and one recipient. More complex systems include numerous providers and numerous recipients plus intermediate phases, e.g. crossdocking,which makes the system structure and relations among its elements more complex.