Just-in-Time (JIT) is an inventory management approach of having the exact amount of inventory goods arriving at the exact time when needed. This paper investigates the impact of this approach on South African Inventory Management systems and the organization as a whole, by comparing two companies producing same products (bed mattress), with different suppliers, and with different inventory management system. Company X has not implemented the Just-in-time approach, while, Company Y has implemented the JIT approach. This paper will provide insight knowledge on the benefits and challenges of this approach, how it can be implemented to improve the performance of a company. Mixed-methods research design has been utilized as a part of this investigation, and descriptive statistics were used to summarize the data collection. From the study conducted it may be concluded that not implementing the JIT system is the causes of lower performance rates, compared to the performance of the company that has. The JIT approach has methods or guidelines on how the company can improve its inventory management system and improve the performance of the company. It is then recommended that organizations in the manufacturing industry implement the Just-In-Time method in their inventory management systems.