Electronic Data Interchange (EDI) is an increasingly important application of computer communications. Until recently, EDI has developed independently of the communications technology and related standards. EDI users coped with this situation by setting up bilateral communication agreements or by using the services of Value Added Data Services centres, which provided protocol conversion. The introduction of X.400 MHS based systems and services is slowly modifying the general attitude towards EDI communications. For the first time, a CCITT rapporteur group is drafting a recommendation for EDI communications within the context of X.400 MHS. More importantly, there already exist official guidelines, both in the U.S.A. and in Europe, which explain how to take advantage of X.400 MHS systems today. The purpose of this paper is to comment upon these first approaches to an EDI communication standard. For this reason, and because we expect only a few readers to be familiar with both EDI and X.400 MHS, we begin with introductions to both subjects. Originally published in Computer Communication Review (ACM), vol 20, n. 2, April 1990.