Mortality among males with 47,XYY is increased due to a host of conditions and diseases. Clinical studies have suggested a poorer educational level and social adaptation among 47,XYY persons. We wanted to study the socio-economic profile in 47,XYY persons and the impact on mortality. We conducted a register study using several Danish nationwide registries. 206 47,XYY men and 20,078 controls from the background population and 1,049 controls with Klinefelter syndrome were included. Information concerning marital status, fatherhood, education, income, and retirement were obtained. Compared to the background population, 47,XYY men had fewer partnerships, were less likely to become fathers, had lower income and educational level, and retired at an earlier age. The mortality among 47,XYY men was significantly increased with a hazard ratio (HR) of 3.6 (95% confidence interval: 2.6–5.1). Adjusting for marital and educational status reduced this HR to 2.7. Compared to Klinefelter syndrome, 47,XYY had significantly fewer partnerships, were more likely to become fathers, but had lower income. Mortality among 47,XYY men was increased compared with Klinefelter syndrome with a HR of 1.36. The results show a severely inferior outcome in all investigated socio-economic parameters compared to the background population and an affected profile compared with Klinefelter syndrome, even though the population in Denmark has equal and free access to health care and education. We conclude that 47,XYY is often associated with a poorer socio-economic profile, which partly explains the increased mortality. © 2012 Wiley Periodicals, Inc.