Abstract: An apparatus and method for processing health care transactions through a common interface in a distributed computing environment using specialized remote procedure calls. The distributed computing environment includes a user interface tier for collecting user inputs and presenting transaction outputs, a data access tier for data storage and retrieval of health care transaction information, a transaction logic tier for applying a predetermined set of transaction procedures to user inputs and health care transaction information resulting in transaction output, an electronic network connecting the user interface tier, data access tier and transaction logic tier to each other and a communication interface for exchanging health care transaction information among the tiers. The communication interface includes an interface definition language generating transaction-specific communication codes whereby data is exchanged through a common interface structure regardless of the origin of the data.