Abstract: The aim of this study was to determine the potential of screening breast ultrasound to improve breast cancer detection in women with mammographically normal, but dense breasts. Six Connecticut radiology practices with 12 total sites participated in a retrospective chart review. The total number of screening mammograms, screening ultrasounds broken down by BIRADS (Breast Imaging Reporting and Data System) codes, and the number of positive and negative biopsies were collected from November 2009 through November 2010. Demographic data on the patients with positive biopsies as well as cancer staging were also collected. Sensitivity, Specificity, Positive Predictive Value, and Negative Predictive Value were calculated. A total of 72,030 screening mammograms and 8,647 screening ultrasounds were performed at the research sites during the study period. Relevant research indicates that 41% of the female population has dense breasts. In this study, 12% (8,647/72,030) underwent follow-up breast ultrasound screening. A total of 86% (7,451/8,647) of the ultrasounds were BIRADS 1 or 2, 9% (767/8,647) were BIRADS 3, 5% (429/8,647) were BIRADS 4 or 5. Of those 429 recommended to undergo biopsy 418 were performed and 28 cancers were found. There was one false negative. Screening breast ultrasound in women with mammographically normal, but dense breasts has a Positive Predictive Value (PPV) of 6.7% (28/418), Negative Predictive Value (NPV) of 99.9% (7,450/7,451), sensitivity of 96.6% (28/29), and a specificity of 94.9% (7,450/7,851). Screening ultrasound had an additional yield of 3.25 per 1,000 cancers in women with dense breasts and normal mammograms and no additional risk factors. As with all screening tests, time, cost, and false positive risk must be considered.