The promotion of quality medical treatment is very important to the healthcare providers as well as to patients. It requires that the medical resources of different hospitals be combined to ensure that medical information is shared and that resources are not wasted. A computer-based patient record is one of the best methods to accomplish the interchange of the patient's clinical data. In our system, the Health Level/Seven (HL/7) format is used for the interchange of the clinical data, as it has been supported by many healthcare providers and become a â standard'. The security of the interchange of clinical data is a serious issue for people using the Internet for data communication. Several international well-developed security algorithms, models and secure policies are adopted in the design of a security handler for an HL/7 architecture. The goal of our system is to combine our security system with the end-to-end communication systems constructed from the HL/7 format to establish a safe delivery channel. A suitable security interchange environment is implemented to address some shortcomings in clinical data interchange. located at the application layer of the ISO/OSI reference model. The medical message components, sub-components, and related types of message event are the primary goals of the HL/7 protocols. The patient management system, the doctor's system for recording his advice, examination and diagnosis as well as any financial management system are all covered by the HL/7 protocols. Healthcare providers and hospitals in Taiwan are very interested in developing the HL/7 protocols as a common standard for clinical data interchange.