Study objectives: to evaluate the effects of information about benefits and risks of mammography screening on participants in terms of knowledge, attitude, rates of uptake, fear of cancer, anxiety, and conflict decision. Study hypothesis: information about benefit and risks of mammography screening increases the women´s knowledge of it; allows women to make an informed decision on whether to stop or continue the screening program, changing the actual participation rate; anxiety and fear are not increased. Design: randomized controlled clinical trial with non-pharmacological intervention. Subjects and setting of study: women referred to mammography screening in the District Bay of Cádiz-La Janda. Interventions: random assignment of women in two arms according to the information provided. Control arm is the standard information; it consists of receiving information normally provided to women attending the screening program for breast cancer. Intervention arm is the experimental information and consists of receiving accurate verbal and written information about the benefits and real risks of mammography screening programs by a physician investigator. Determinations: knowledge, attitude, rates of uptake, fear of cancer, anxiety, and conflict decision.