The aim of this study is to analyse the influence of country of birth on body mass index (BMI) after adjustment for age, educational status, physical activity and smoking habits. Two random samples of men and women, aged 27-60, were used: 1,957 immigrants and 2,975 Swedes, both from 1996. Men and women were analysed in separate models by the use of linear regression. The BMI levels were significantly higher among Polish (0.8 BMI units) and Chilean (0.7 BMI units) men, and Chilean (1.9 BMI units) and Turkish (1.5 BMI units) women than among their Swedish controls, after adjustment for all explanatory variables. Other intermediate risk factors for cardiovascular disease, such as physical inactivity and daily smoking, were also more frequent among almost all the immigrant subgroups. This study shows a strong influence of country of birth on BMI even after adjustment for age, educational status, physical activity and smoking habits.