571 Background: Aromatase inhibitors (AIs) have become the standard of care for the treatment of postmenopausal, hormone-sensitive breast cancer (BC). However, patients receiving AIs may experience joint symptoms which can lead to early discontinuation of this effective therapy. We examined whether acupuncture improves AI-induced arthralgias in women with early stage BC. Methods: This study is a randomized, single-blinded trial of true vs sham acupuncture twice weekly for 6 weeks in postmenopuasal women with early stage BC and self-reported musculoskeletal pain related to adjuvant AI therapy. The active intervention included full body/auricular acupuncture and a joint-specific point prescription, whereas the sham arm involved superficial needle insertion at nonacupoint locations. Outcome measures included the Brief Pain Inventory-Short Form (BPI-SF), Western Ontario and McMaster Universities Osteoarthritis Index(WOMAC), and Modified Score for the Assessment and Quantification of Chronic Rheumatoid Affections of the Hands (M-SACRAH) obtained at baseline, 3 and 6 weeks. Lower scores reflect improvement in symptoms. Results: Of 43 women enrolled, 38 were evaluable at 6 weeks. Baseline characteristics were comparable between the groups. Median age: 57 (37–77); White/Hispanic/Black/Asian: 15/21/1/1; median body mass index (kg/m2): 29 (18–45). True acupuncture was associated with about a 50% decrease in mean BPI-SF scores, whereas no change from baseline was observed for the sham acupuncture group (see table). Similar findings were seen for the WOMAC and M-SACRAH pain, stiffness, and function scores (P<0.05). No adverse events were reported. Conclusions: Women with AI-induced arthralgias treated with acupuncture had significant improvement of joint pain and stiffness, which was not seen with sham acupuncture. Acupuncture is an effective and well-tolerated strategy for managing this common treatment-related side effect. [Table: see text] No significant financial relationships to disclose.