184 Background: The initial ASCO “Top 5” list, created as part of the Choosing Wisely campaign, recommends against use of imaging for staging of early stage breast cancer in asymptomatic women at low risk for metastasis. The objective of this study was to measure and compare use of imaging for staging in two large integrated health care systems, Kaiser Permanente (KP) and Intermountain Healthcare (IH). We also sought to distinguish whether imaging was used for routine staging or for diagnostic purposes. Methods: We identified stage 0-IIB breast cancer patients diagnosed between January 1, 2010 and December 31, 2012 with first primary malignancy from tumor registries in three KP regions (Southern California, Northwest, and Mid-Atlantic) and IH. Using the KP and IH electronic health records, we identified use of imaging tests (PET, CT, bone scan) during the staging window (30 days prior to diagnosis up to initial surgery). We performed chart abstraction on a random sample of patients who received an imaging test to identify indication. Results: For the total sample of 10,014, mean age at diagnosis was 60 (range 22-99); with 21% stage 0, 47% stage I, 32% stage II. Overall, 8% of patients (792 patients) received at least one imaging test during the staging window, including 8% at KP and 6% at IH (p=0.0005). Chart abstraction (N=129) revealed that overall, almost half of all imaging tests (48%) were performed to evaluate a symptom, sign or prior imaging finding, including 55% at KP and 32% at IH. Conclusions: Use of imaging for staging of low-risk breast cancer was very low in both health care systems, with clinically trivial differences between them. Approximately half of imaging services were in response to a sign or symptom. Strategies to reduce use of imaging at staging for early stage breast cancer patients within these health care systems are unlikely to yield meaningful improvement. [Table: see text]