The aim of this study was to analyse the independent role of socio-demographic factors on the use of mammography according to whether or not an organized breast cancer screening programme exists. The study sample of 2825 women aged 40-74 years was drawn from a cross-sectional population-based survey of French households. Among these women 46% lived in districts that offered a screening programme and 63% reported undergoing mammography in the previous 2 years. Living in a district that offered a screening programme was associated with increased use of mammography. According to both univariate and multivariate analysis, several socio-demographic characteristics, such as high monthly household income or high education level, increased the probability of using mammography. However, three factors had a major positive impact on its use: (1) having had a gynaecological examination in the previous 2 years, (2) living in a district where a screening programme was available, and (3) age. There was a significant interaction between the factors 2 and 3. Between 40 and 60 years, age had the same impact on the use of mammography whether or not women lived in a district with a screening programme. After the age of 60 years, the use of mammography collapsed among women living in a district without a screening programme and remained frequent among women living in the district that offered such a programme. Even if the overall level of mammography screening was high and the existence of a screening programme maintained a high level of mammography use among older women, the programme should target better the women of underprivileged spheres and reinforce the role of the general practitioner; in particular for women not followed by a gynaecologist.