IMPORTANCE: Aromatase inhibitors (AIs) have proven efficacy for the treatment of hormone-sensitive breast cancer; however, arthralgias (pain and stiffness) contribute to nonadherence with therapy for more than 50% of patients. OBJECTIVE: To examine the effect of acupuncture in reducing AI-related joint pain through 52 weeks. DESIGN, SETTING, AND PARTICIPANTS: A randomized clinical trial was conducted at 11 sites in the US from May 1, 2012, to February 29, 2016, with a scheduled final date of follow-up of September 5, 2017, to compare true acupuncture (TA) with sham acupuncture (SA) or waiting list control (WC). Women with early-stage breast cancer were eligible if they were taking an AI and scored 3 or higher on the Brief Pain Inventory Worst Pain (BPI-WP) item (score range, 0-10; higher scores indicate greater pain). Analysis was conducted for data received through May 3, 2021. INTERVENTIONS: Participants were randomized 2:1:1 to the TA (n = 110), SA (n = 59), or WC (n = 57) group. The TA and SA protocols were composed of 6 weeks of intervention at 2 sessions per week (12 sessions overall), followed by 6 additional weeks of intervention with 1 session per week. Participants randomized to WC received no intervention. All participants were offered 10 acupuncture sessions to be used between weeks 24 and 52. MAIN OUTCOMES AND MEASURES: In this long-term evaluation, the primary end point was the 52-week BPI-WP score, compared by study group using linear regression, adjusted for baseline pain and stratification factors. RESULTS: Among 226 randomized women (mean [SD] age, 60.7 [8.6] years; 87.7% White; mean [SD] baseline BPI-WP score, 6.7 [1.5]), 191 (84.5%) completed the trial. In a linear regression, 52-week mean BPI-WP scores were 1.08 (95% CI, 0.24-1.91) points lower in the TA compared with the SA group (P = .01) and were 0.99 (95% CI, 0.12-1.86) points lower in the TA compared with the WC group (P = .03). In addition, 52-week BPI pain interference scores were statistically significantly lower in the TA compared with the SA group (difference, 0.58; 95% CI, 0.00-1.16; P = .05). Between 24 and 52 weeks, 12 (13.2%) of TA, 6 (11.3%) of SA, and 5 (10.6%) of WC patients reported receipt of acupuncture. CONCLUSIONS AND RELEVANCE: In this randomized clinical trial, women with AI-related joint pain receiving 12 weeks of TA had reduced pain at 52 weeks compared with controls, suggesting long-term benefits of this therapy. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT01535066.