Developed logistics systems have organized reverse logistics flows and are continuously analyzing product returns, tending to detect patterns in oscillations of returning products in certain time periods. Inventory management in reverse logistics systems depends on different criteria, regarding goods categories, formed contracts between subjects of supply chains, uncertainty in manufacturer's quantities of DOA (dead on arrival) products, etc. The developing logistics systems, such as the Croatian system, find reverse logistics issues overall, also regarding returned products inventory management, significantly complex, and do not provide systematic analysis. The paper discusses the problem of reverse logistics flow processing, detects current return quantities locked in inventories and suggests systematic application of analysis as the first step to organize inventories in unorganized reverse logistics systems.