Cross sectional population studies have shown that subjects who are severely obese are of lower social class than comparable subjects who are not obese. This may be ascribed to lower parental social class, poorer education, and lower intelligence test scores of the obese subjects. In this study based on 242 633 draftees appearing before the draft board in Copenhagen between 1956 and 1977, 1144 extremely overweight men (body mass index greater than or equal to 31 kg/m2) were compared with 2123 young men randomly chosen from the remainder of the population. The two groups were followed up for an average period of 12 X 5 years, after which time their occupation was obtained from the National Population Register. Social class was derived from a ranking of occupations based on prestige from 0 (unskilled, manual worker) to 7 (for example, judge, professor). Among the obese subjects, only 300 (30%) out of 1006 attained a position above social class 2, compared with 988 (51%) out of 1948 in the control group. At each level of education and intelligence test score, as registered at the draft board, the obese subjects still showed a significantly lower attainment of social class than the controls. Inclusion of parental social class, information which was available for part of the population, did not eliminate the difference in attainment of social class. The results of this study show that obese subjects not only suffer from a higher risk of somatic diseases but have to live with a social handicap that is independent of parental social class, intelligence, and education.