Social class differences in health in the UK have usually been demonstrated by the Registrar General's social classification (RGSC). It is being replaced by the new UK National Statistics Socio-Economic Classification (NS-SEC). The NS-SEC is explicitly based on differences between employment relations and conditions. The mechanisms underlying social class differences in health remain debatable. Some studies have hypothesised that class differences in work characteristics and employment conditions may explain part of the observed class differences in health. This study investigates the associations of the NS-SEC and other measures of socio-economic status (SES) with mortality outcomes in a 7-year panel study representative of British private households and their members (the British Household Panel Survey, n = 10264). The NS-SEC was neither significantly associated with mortality for respondents of all ages nor with mortality for a younger subsample who were under 65 years at the initial survey. Other measures of SES, especially income and housing tenure showed significant patterns of inequalities in mortality. It may be useful to use other measures of SES along with the NS-SEC when analysing social inequalities in health and mortality.