This analysis of mortality in women aged 25-59 in 2001-03 found that those in the least advantaged social economic class had a mortality rate around twice that of women in the most advantaged class. This article uses the National Statistics Socio-economic Classification (NS-SEC) and examines the relative merits of classification based on a woman's 'own' occupation as opposed to a 'combined' classification which also takes into account the husband's NS-SEC class, where available. The results demonstrate a strong socio-economic gradient in mortality for adult women under both classification methods. Under the 'combined' classification, women in the least advantaged NS-SEC class had a mortality rate 2.6 times that of those in the most advantaged class. Based on the women's'own' occupation, the comparable ratio was 1.9. These results set a benchmark for the future monitoring of socio-economic mortality inequalities in women, and also provide a comparison between inequalities affecting women and men.