Objective: To explore the factors that influence attitudes and beliefs about the effects of body weight and physical activity on health. Design: Cross-sectional survey using a face-to-face interview-assisted questionnaire. Setting: The survey was conducted between March and April 1997 in the 15 member states of the EU. Subjects: Approximately 1000 adults aged 15 years plus from each country were selected by quota-controlled sampling; the total sample was of 15 239 persons (7162 males and 8077 females). Data were weighted by population size for each country and by age, gender and regional distribution within countries. Results: Overall 27% of men and 35% of women reported not engaging in any form of recreational activity; rates were highest in those with a primary-level education (37% men, 43% women) compared with tertiary-level education (20% men, 25% women). Recreational activity levels declined with age and tended to be lowest in those who were more physically active at work. Eighteen per cent of respondents believed that physical activity was one of the two greatest influences on health; 13% mentioned body weight, 38% mentioned food, 41% mentioned smoking and 33% mentioned stress. Logistic regression was used to assess for the effects of gender, age, educational level, body mass index (BMI), smoking status, activity level and country on beliefs that body weight and physical activity influenced health. Primary-educated, overweight, ex-and non-smoking women were most likely to mention body weight as an influence; young tertiary-educated, thinner, non-smoking and active males were most likely to mention physical activity. There was wide variation across Europe in reported behaviour and beliefs, which persisted after taking account of all of the other factors in the regression model. Conclusions: Relatively few people in some countries believed body weight and physical activity were important influences on health. Many people mentioned stress and it might be possible to use this interest to motivate changes in physical activity to relieve stress. It may be important to take a more integrated approach to activity patterns that consider the role of work and recreation. Although social and demographic factors were important, after adjusting for these factors there was still wide between-country variation in reported attitudes, beliefs and behaviour. This will need to be taken into account in any activity promotion campaigns.