Prehospital 12-lead electrocardiographic (ECG) diagnostic strategies have been proven feasible and effective, provided they are designed and implemented properly. The authors of this communication have expended considerable time and effort in determining appropriate planning, implementation, and process monitoring necessary for successful implementation of a variety of prehospital diagnostic strategies. Many of these issues may not be obvious to an emergency medical services (EMS) director initiating a 12-lead ECG program. This level of attention to protocol development, education, training, inservice education, coordination of the health-care community, objective program assessment, monitoring and continuos quality improvement can serve as a model for other diagnostic EMS programs that may develop as an expanded role for EMS.