This study aimed to investigate the extent of applying just-in-time production system on maximizing profitability of small and medium industrial companies in Jordan, where maximizing profitability of companies represented in both (reducing product costs and reducing ending inventory obsolescence) for those companies. In order to achieve the objectives of the study, a questionnaire was designed as a tool for study and was distributed to the study sample represented by administrative managers and financial managers in small and medium industrial companies. The study community consisted of (235) companies of small and medium industrial companies. The Robert Mason equation was used to determine the sample size which consisted of 146 companies, where this study distributed 292questionnaires, and 217 of them were received, while 33 questionnaires were excluded, and the final sample was 184 questionnaires. The results of the study showed that there is a statistically significant impact of applying just-in-time production system on maximizing profitability of small and medium industrial companies in Jordan, and there is a statistically significant impact of applying just-in-time production system on (reducing product costs and reducing ending inventory obsolescence) in small and medium industrial companies. The Study recommended a number of recommendations, the most important of which is: It is necessary to review the successful experiences of international companies that adopt applying just-in-time production system, and to benefit from them by small and medium industrial companies in Jordan in applying just-in-time production system as an advanced tool for cost management and thus maximizing their profitability.