STUDY OBJECTIVE To quantify and investigate differences in survival from breast cancer between women resident in affluent and deprived areas and define the contribution of underlying factors to this variation. DESIGN Analysis of two datasets relating to breast cancer patients in Scotland: (1) population-based cancer registry data; (2) a subset of cancer registration records supplemented by abstraction of prognostic variables (stage, node status, tumour size, oestrogen receptor (ER) status, type of surgery, use of radiotherapy and use of adjuvant systemic therapy) from medical records. SETTING Scotland. PATIENTS (1) Cancer registration data on 21,751 women aged under 85 years diagnosed with primary breast cancer between 1978 and 1987; (2) national clinical audit data on 2035 women aged under 85 years diagnosed with primary breast cancer during 1987 for whom adequate medical records were available. MAIN RESULTS Survival differences of 10% between affluent and deprived women were observed in both datasets, across all age groups. In the audit dataset, the distribution of ER status varied by deprivation group (65% ER positive in affluent group v 48% ER positive in deprived group; under 65 age group). Women aged under 65 with non-metastatic disease were more likely to have breast conservation than a mastectomy if they were affluent (45%) than deprived (32%); the affluent were more likely to receive endocrine therapy (65%) than the deprived (50%). However, these factors accounted for about 20% of the observed difference in survival between women resident in affluent and deprived areas. CONCLUSIONS Deprived women with breast cancer have poorer outcomes than affluent women. This can only partly be explained by deprived women having more ER negative tumours than affluent women. Further research is required to identify other reasons for poorer outcomes in deprived women, with a view to reducing these survival differences.