This study focuses on empirical analysis of total JIT system implementation`s effect on supply chain performance. Total JIT system implies an integrated implementation of JIT operation, JIT purchasing and JIT selling. Based on 128 manufacturing business unit surveys in Korea, three proposed total JIT system constructs (JIT operation, JIT purchasing and JIT selling) were tested and refined through confirmatory factor analysis and internal consistency analysis. JIT operation outperformed the other two in explaining the overall supply chain performance and seemed to serve as a fundamental factor for better supply chain performance. Output supply chain performance such as sales volume, net profit, fast order fulfillment, delivery error, customer complaints showed a significant relationship with JIT operation. Mix flexibility and product flexibility also showed a positive close relationship with JIT operation. JIT selling showed a significant positive relationship with two flexibility performances (volume flexibility and delivery flexibility) as well as fast order fulfillment. However, JIT purchasing came up with no significant relationship with a single supply chain performance.