For more than a decade, trust and commitment have received much attention in marketing channels literature. This study investigates the effects of these two core relational dimensions on the performance of EDI-supported marketing channels. A survey of the 92 suppliers of large department stores in Korea indicates that commitment to EDI increases significantly the organizational and economic performance of EDI-supported marketing channels. Trust was found to increase EDI performance indirectly by enhancing commitment to EDI. Based on the Social Information Processing(SIP) theory the present study also explored the effects of time on trust and commitment to EDI and their impacts on EDI performance. Analyses supported the hypothesized time effects that trust and commitment to EDI develop positively as EDI moves from initial stage to application stage. However, the impacts of these two dimensions on EDI performance did not change significantly over time.