The Epidemic Intelligence Service (EIS) - the two year applied epidemiology training programme of the United States (US) Centers for Disease Control and Prevention (CDC) - celebrates its 50th anniversary in 2001. Developed during the Korean war, only five years after CDC was established, the stimulus behind developing the EIS was a lack of trained field investigators should biological agents be intentionally used against the US population. It was, however, clear to Alexander Langmuir, the head of epidemiology at CDC and founder of the EIS, that his trainees would engage in a wide range of activities and help fill gaps in the US for epidemiologists with the skills and practical field experience to investigate and control naturally occurring outbreaks of diseases.