BACKGROUND:Delays in abnormal mammogram follow-up contribute to poor outcomes. In the current study, the authors examined differences in abnormal screening mammogram follow-up between non-Hispanic white (NHW) and Asian women. METHODS:The authors used a prospective cohort of NHW and Asian women with a Breast Imaging, Reporting and Data System (BI-RADS) abnormal result of category 0 or 3-plus in the San Francisco Mammography Registry between 2000 and 2010. Kaplan-Meier estimation for the median number of days to follow-up with a diagnostic radiologic test was performed, and the authors compared the percentage of women with follow-up at 30 days, 60 days, and 90 days and no follow-up at 1 year for Asian women overall (and Asian ethnic groups) and NHW women. In addition, the authors assessed the relationship between race/ethnicity and time to follow-up with adjusted Cox proportional hazards models. RESULTS:Among Asian women, Vietnamese and Filipina women had the longest, and Japanese women the shortest, median follow-up (32 days, 28 days, and 19 days, respectively) compared with NHW women (15 days). The percentage of women receiving follow-up at 30 days was lower for Asians versus NHWs (57% vs 77%; P<.0001), and these disparities persisted at 60 days and 90 days for all Asian ethnic groups except Japanese. Asian women had a reduced hazard of follow-up compared with NHW women (adjusted hazard ratio, 0.70; 95% confidence interval, 0.69-0.72). Asian women also had a higher rate of receiving no follow-up compared with NHW women (15% vs 10%; P<.001); among Asian ethnic groups, Filipinas were found to have the highest percentage of women with no follow-up (18.1%). CONCLUSIONS:Asian women, particularly Filipina and Vietnamese women, were less likely than NHW women to receive timely follow-up after an abnormal screening mammogram. Research should disaggregate Asian ethnicity to better understand and address barriers to effective cancer prevention. Cancer 2017;123:3468-75. © 2017 American Cancer Society.