The implications of the eradication of smallpox in the context of epidemiology are presented. Eradication of disease has been conceived since the 1st smallpox vaccination was developed in the 18th century. Since then, attempts to eradicate yellow fever, malaria, yaws and smallpox have been instituted. Most public health professionals have been rightfully skeptical. Indeed, the success with smallpox was fortuitous and achieved only by a narrow margin. It is unlikely that any other disease will be eradicated, lacking the perfect epidemiological characteristics and affordable technology. The key to success with smallpox was the principle of surveillance. This concept has a vigorous developmental history in the discipline of epidemiology, derived from the work of Langmuir and Farr. It involves meticulous data collection, analysis, appropriate action and evaluation. In the case of smallpox, only these techniques permitted the key observations that smallpox vaccination was remarkably durable, and that effective reporting was fundamental for success. The currently popular goal of health for all, through horizontal programs, is contrary to the methods of epidemiology because its objective is vague and meaningless, no specific management structure is envisioned, and no system of surveillance and assessment is in place.