BACKGROUND: Regular mammography accounts for half of the recent declines in breast cancer mortality. Mammography use declined significantly in 2008. Given the success of regular breast cancer screening, understanding why mammography use decreased is important. We undertook a focus group study to explore reasons women who were previously adherent with regular mammography no longer were screened. METHODS: We conducted 20 focus groups with white non-Hispanic, black non-Hispanic, Hispanic, Japanese American, and American Indian/Alaska Native women, and segmented the groups by age, race/ethnicity, and health insurance status. A conceptual framework, based on existing research, informed the development of the focus group guide. Discussion topics included previous mammography experiences, perceptions of personal breast cancer risk, barriers to mammography, and risks and benefits associated with undergoing mammography. Atlas.ti was used to facilitate data analysis. RESULTS: All focus groups (n=128 women) were completed in 2009 in five cities across the United States. Half of the groups were held with white non-Hispanic women and the remainder with other racial/ethnic groups. Major barriers to routine mammography included (1) concerns about test efficacy, (2) personal concerns about the procedure, (3) access to screening services, (4) psychosocial issues, and (5) cultural factors. For uninsured women, lack of health insurance was the primary barrier to mammography. CONCLUSIONS: Multilevel interventions at the health-care provider and system levels are needed to address barriers women experience to undergoing regular mammography screening. Ultimately, breast cancer screening with mammography is an individual behavior; therefore, individual behavioral change strategies will continue to be needed.