OBJECTIVES: Estimate national trends in mammography screening use among elderly Medicare beneficiaries for the period of 1998 to 2001; determine the extent to which socio-demographic, clinical, and access factors are associated with disparities in screening use. METHODS: A secondary data analysis of the Medicare Current Beneficiary Survey (MCBS) was conducted. Community-dwelling women aged >65 years who completed the MCBS at least once during the survey years of 1998 to 2001 were included. Having had a mammogram in the past year was determined by a participant's response to the question “have you had a mammogram or a breast x-ray since a year ago?”, or by a Medicare claim coded with a mammogram procedure in the calendar year. Multivariate logistic regression was used to estimate the association between the likelihood of having had mammogram in the past year and factors, such as socio-demographic, biological, and access factors. Sampling weights were used to reflect national estimates of Medicare beneficiaries. Standard errors were adjusted for clustering and stratification in the complex sampling design. RESULTS: A total of 10,757 females 65 years of age or older responded to the MCBS from 1998 to 2001 (weighted N=34 million). Over half (54%, 95% CI 53%-55%) of the respondents had mammogram in the past year. Annual mammography screening rates increased over time, from 49% in 1998 to 58% in 2001. In adjusted models, there was no significant racial or ethnic disparity in mammography use, but the other socio-demographic factors remained significantly associated with lower odds of mammography use. CONCLUSIONS: Mammography screening rates increased notably between 1998 and 2001 in the Medicare population. While no racial or ethnic disparities in screening rates were noted in this study, lower income, less education, no insurance and being unmarried were identified as barriers to breast cancer screening for elderly Medicare beneficiaries.