Recently firms which have been using traditional VAN-EDI are adapting Web-EDI at very rapid pace. Based on the Internet, Web-EDI is easier to install, is cheaper and more accessible than VAN-EDI. Web-EDI establishes an electronic hierarchy as a type of Inter-Organization Information System. An electronic hierarchy connects two legally separate firms in an electronically mediated relationship. The primary reasons for establishing an electronic hierarchy is to improve the flow of materials and information between firms. This paper suggests two hypotheses that describe the possible impact of Web-EDI on firms in the Web-EDI network, and empirically tests them using data from a case study based on a discount store. The result is as follows. First, the more a firm utilizes information shared through Web-EDI, the higher the inventory turns. Second, a higher level of information sharing does not necessarily increase the inventory turns of Web-EDI adopters who are coerced to implement the electronic networks by the champion. These findings imply that the operational performance of Web-EDI adopters can be improved only when the firms intensively utilize the information shared through Web-EDI for their business processes.