This paper describes the introduction of electronic data interchange (EDI) into the Scottish Health Service during a period of organisational flux caused by the introduction of an internal market in health care provision. The Scottish Health Service's central provider of IT services--the Common Services Agency (CSA)--attempted to develop a coherent EDI strategy, which would also have supported its role in the organisational status quo. However, the very weakness of its organisational power base which it sought to bolster in this way meant that the EDI strategy did not proceed rapidly or smoothly, and this then provided the opportunity for supplier companies to advance their own strategic aims through the implementation of proprietary EDI systems. The case study thus raises doubts about the extent to which EDI can be promoted and guided by public administration.