PURPOSE: To evaluate whether there is an association between the number of months since previous mammography (MSPM) and performance measures (sensitivity, specificity, recall rate, cancer detection rate, and positive predictive value) in women who underwent U.S. community-based screening mammography. MATERIALS AND METHODS: Data from seven registries (Breast Cancer Surveillance Consortium) and mammographic data and cancer outcome in regard to 1 213 754 screening mammographic examinations performed in 680 641 women who were 40-89 years old for the years 1996-2000 were used in this study. These data are submitted annually in a standard format to a central statistical coordinating center that is subject to institutional review board approval, quality control, and confidentiality standards. Performance measures were calculated for first and subsequent screening mammography. For subsequent mammography, performance measures were calculated according to categories of MSPM (9-15, 16-20, 21-27, and ≥28 months). Receiver operating characteristic and multivariable logistic regression analyses were conducted to test the association between the number of MSPM and performance measures. RESULTS: With increasing MSPM in each category from 9-15 to 28 months or more and for first mammographic examinations, respectively, there was increased sensitivity (70.9%, 75.7%, 85.4%, 82.5%, and 88.6%), decreased specificity (93.3%, 92.7%, 91.6%, 91.0%, and 85.9%), increased recall rate (7.0%, 7.6%, 8.8%, 9.4%, and 14.7%), and increased cancer detection rates (3.2, 3.5, 4.5, 4.6, and 6.1 per 1000 mammographic examinations). When the category of 9-15 MSPM was compared with that of 21-27 MSPM, there was a slight increase in positive predictive value from 4.6% to 5.1%. Confidence intervals were narrow and did not overlap. Age affected these associations for aii performance measures except sensitivity. CONCLUSION: Performance measures increased as MSPM increased, except for specificity, which decreased. Time between mammograms is an important factor to consider when audits are reviewed or screening performance measures are compared. © RSNA, 2005.