Virtually all major pharmaceutical companies have deployedfield-based medical support programs. Since 1967, medical liaison personnel have supported a range of customers, including opinion leaders, investigators, and health care decision makers. This article summarizes the history of field-based medical programs, and provides results of a 1999 pharmaceutical industry medical informution survey and information on establishing a regional liaison program. Technological advances, consolidation of decision making, and the increasing complexity of health care decisions will mandate the need for continued field medical program development and expansion.