With the rapidly changing external environment and the increasing internal process complexity, more and more organizations are adopting the Electronic Approval Systems(EAS) for their competitiveness. This paper defines EAS as a core organizational communication medium, investigates factors which influence EASs use from a media rich-ness theory, and shows suitable EAS functions for equivocality resolution and uncertainty reduction. Results from the five EAS implementation sites show that most organizations use EAS only for tasks with low equivocality and low uncertainty. Additional functionalities such as video conferencing and database access suggested for fu-ture EAS system to enhance their their utilization for more critical and unstructed tasks.