Breast cancer is the most common type of cancer among women, and the leading cause of cancer deaths worldwide. Among early detection methods, screening by mammography has been used in most developed countries as gold standard. The goal of this study was to evaluate the difficulties and opportunities in implementing breast cancer screening in Brazil, with an emphasis on the diagnostic methods used according to stage distribution. Between 2007 and 2009, 248 women were diagnosed with breast cancer in the Barretos region. Most of these were interviewed in their homes using a questionnaire with sociodemographic and preventive breast cancer screening questions. All other data were obtained from Barretos Cancer Hospital (BCH) medical records. The screening program conducted by BCH was responsible for 46.1% of diagnosed cases, with 30.1% of these referred from the private system and 23.8% from the public system. Among asymptomatic women screened by the BCH Screening Program 70.8% had clinical stage 0-I disease, compared with 58.1% in the private and 50% in the public systems. Monthly breast self-examination was reported by 48.5% of the women. Clinical breast examinations were regularly performed by 88.9% of gynecologists in the private and 40.7% in the public health systems. Only 5.6% of the women reported difficulty in accessing mammography and this was most frequently due to fear of the disease or lack of knowledge about mammography in asymptomatic women. This breast cancer screening program resulted in a substantial number of patients presenting with clinical stage (CS) 0-I disease. The success of this program was due to intensive community interventions, free mammography, and the availability of health care and mammography close to patients' homes.