The issue of confidentiality and invasion of privacy has become increasingly prominent as the use of computing and communication technologies becomes widespread. The importance of individual privacy has long been recognized in a democratic society. Laws and regulations, such as privacy and freedom of information acts, have been introduced to assure and safeguard individual rights. However, the meaning and actual requirements of information and data security for protecting these rights has not been clearly understood. Information security concerns in health care delivery information systems are particularly sensitive. This plenary address is intended to stimulate discussions at the conference on identifying and representing information security requirements and semantics for the development of security policies and enforcement techniques for healthcare delivery information system.