Background Breast cancer is the most common malignant tumor in women in the world. In 2005, it was incorporated to the Explicit Guaranties Health System (GES) in Chile. Aim To describe the demographic and clinical characteristics of breast cancer patients and to determine the effect of incorporating these women to GES. Material and Methods Medical records of 5,119 women with breast cancer aged 59 ± 14 years, attended at six public hospitals between 2000 and 2010 were reviewed. Median follow up was 87 months (range 1-182). Mortality was assessed using death certificates obtained at the National Identification Registry. Results Sixty six percent of women were in stage I-II, 29% in stage III and 5% in stage IV. Surgery was performed in 4023/5119 cases (79%), adyuvant radiotherapy in 3627/4517 cases (80%), chemotherapy in 3,204/3,424 cases (94%) and hormone therapy in 1,695/2,375 cases (71%). Between 2000 and 2010, there was a significant increase in the proportion of cases in stage I, from 8% to 25%, (p < 0.01). Overall survival (OS) increased 1% per year, since the beginning of GES system (p = 0.024). Five year OS was 75.1%. The figures for Stage I, II, III and IV were 93, 84, 62 and 27% respectively (p < 0.01). Patients without lymph node involvement and who were not triple negative, had a significantly better OS. Conclusions There was a significant increase in stage I cases, and a 1% per year OS improvement after GES system started, compared with the previous period.