OBJECTIVES: Women's participation in organized screening of breast cancer was 52% in France and 40% in the Île de France in 2010. We wanted to investigate the reasons for non-participation in the screening program and the reluctance of women to it at the level of a department in Île de France. MATERIALS AND METHODS: An anonymous questionnaire was sent to non-respondents in organized screening for breast cancer in the Yvelines department in September 2011 on the occasion of the event "Octobre Rose", month of national mobilization for mass screening for breast cancer. The analysis of these questionnaires was used to determine the causes of non-adherence to organized screening and reluctance to it. We compared the questionnaire responses in the characteristics of patients attending an individual screening with those of patients without any screening. RESULTS: Two thousand nine hundred and ninety-two questionnaires were sent and 3026 responses received (10%). Two thousand six hundred and fifteen women (86%) reported regular screening and make mammograms every two years while 411 (14%) reported occasional or no screening. About the reluctance to conduct the review, the lack of time, the bad memories of a previous mammogram and the fear of pain were the predominant brakes. Nearly 50% of women do not participate in screening because they did not consider themselves at risk for various reasons (lack of symptoms, healthy lifestyle and no family history) and 22% of women surveyed had an attitude of denial cope with the disease. The typical profile of women performing individual or organized screening of breast cancer was that young, single, working, of low socio-professional category and rarely attending their general practitioner or gynaecologist. Health-care professionals seem most likely to cause adherence to screening for breast cancer. DISCUSSION AND CONCLUSION: Focusing on the poor communication and promote organized screening instead of individual screening by health-care professionals themselves could increase adherence to organized screening in the Yvelines.