The identification and quantitation of environmental risk in humans is one of the main problems to be solved in order to improve the protection of individuals and of human populations against phys­ ical and chemical pollutants. Epidemiology plays a central role in the evaluation of health risk directly in human populations. In this volume are collected 33 lectures presented at the AS! course on "Epidemiology and quanti tat ion of environmental risk in humans from radiation and other agents: potential and limitations", sponsored by NATO and Italian Association of Radiobiology and or­ ganized by ENEA. The course has been devoted to a number of aspects of environmental risk analysis and evaluation based on epidemiological in­ vestigation. Basic epidemiological concepts and methods have been reviewed. Fundamentals of dosimetry and microdosimetry were presented in relation to the contribution of epidemiology in defining the dose­ effect relationships for radiation carcinogenesis and its relation with age, sex and ethnicity. The mechanisms of carcinogenesis as a multi-stage process were illustrated. One of the main topics was 'cancer epidemiology' and its cor­ relation with: - occupational and non-occupational exposure to radiation - diagnostic and therapeutic irradiation - cancer proneness - hereditary and familiar diseases - abnormal response to carcino­ gens - environmental pollution in air and water - exposure to radon in mines and in building material - atomic bomb explosion - chemo­ therapy - dioxin and related compounds.