Effective prehospital treatment of the severely injured and acutely ill by an Advanced Emergency Care system may change symptoms and signs by the time patients arrive at the hospital. To provide optimal care, physicians must appreciate the capabilities and limitations of the EMT-paramedic. The EMT-paramedic must report verbally and via written record the course of prehospital events. Cardiac rhythms must be documented for review. It should be the responsibility of the medical directors of such Advanced Emergency Care systems to provide supervision, refresher training, critiques, and evaluation, to establish medical responsibility and credibility.