Questionnaire data were collected covering a broad spectrum of lifestyle and health factors. For the seven initial EPIC countries (France, Italy, Spain, the United Kingdom, the Netherlands, Greece, and Germany), a common set of questions was agreed upon and translated into national questionnaires. This included items related to education and socioeconomic status; current job, current and past occupation, which might have led to exposure to carcinogens; history of previous illnesses, disorders, or surgical operations; lifetime history of tobacco smoking; lifetime history of consumption of alcoholic beverages; physical activity (occupational, walking, cycling, gardening, housework, physical exercise, climbing stairs); menstrual and reproductive history; and use of exogenous hormones for contraception and postmenopausal replacement therapy. In Denmark, Sweden, and Norway and in the Naples centre in Italy, which joined EPIC at a later stage, questionnaires on non-dietary variables had been developed quite independently of those in the initial EPIC countries. Nevertheless, those questionnaires do cover to a large extent the same variables, even if these were not defined in exactly the same manner as for the rest of EPIC. A comprehensive recoding scheme was developed for standardization of the questionnaire variables from these study centres, to make the codes as close as possible to those of the core EPIC lifestyle questions.