Electronic Data Interchange (EDI) implementation is viewed as an important tool for transmission of business data. Yet, its implementation has not reached the predicted level whereby the implementation is often stalled at infancy stage. Many factors were pinpointed as inhibitors or barriers for success of EDI implementation. This study examines key EDI influencing factors and their relationship with implementation level, firm size and type of users. Mail surveys on 108 manufacturers were the main data collection method. Findings indicate that implementation level differs based on influencing factors, while these factors differ based on type of users and do not differ based on firm size. Relatively, internal factors were found to be more significant than external factors. This study also recommends future research to further examine influences of users’ type with different EDI aspects.