Introduction. Breast cancer shows a significant increasing incidence in Colombia, currently about 30 per 100.000 women. Early detection by screening programs generates the opportunity for better management and a more favorable prognosis. This study aims to determine the incidence of breast cancer in women voluntarily attending the early breast cancer detection program by screening mammography at Hospital Universitario, Neiva, Colombia, in the period June 1 to September 30, 2007. Materials and methods. Transverse cohort gratuitous study in patients older than 40 years in the lower socioecomic strata voluntarily wishing to participate; 848 women were included, and demographic, clinical, and diagnostic variables were analyzed. Results and discussion. The diagnosis of early breast cancer was confirmed in 18 patients (2.1%); most frequent was stage IIB (44.4%), followed by stage IIA (38.9%); these findings differ from those of the Instituto Nacional de Cancerologia (National Cancer Institute of Colombia), where breast cancer appears in more advanced stages. It becomes imperative to implement policies oriented toward the detection of early breast cancer, so as to improve survival and prognosis in patients with mammary cancer.