Abstract Objectives: Breast cancer survivors need a non-hormonal treatment for vaginal dryness, as estrogen replacement therapy is often contraindicated or undesired. Therapeutic ultrasound applied to the vaginal introitus is safe and was shown to increase vaginal temperature and blood flow in our phase I study. We now report results from a twelve-week trial of daily, self-applied therapeutic ultrasound to the vaginal introitus. Methods: Breast cancer survivors and post-menopausal women with symptomatic vaginal atrophy were enrolled. A gynecologic oncologist supervised participants in application of a gel-pad equipped ultrasound head (Intelect TranSport, Chattanooga Group) to the vaginal introitus at an enrollment visit, and instructed women on self-application. Daily, 8-minute treatment applications for 12 weeks were planned, and dose was titrated as needed for comfort. Vaginal Maturation Index (VMI) specimens were collected and Vaginal Health Index (VHI) was recorded at study visits. Patient-reported outcomes for vaginal dryness and personal lubrication were recorded on a Likert-type scale (0-3). Student's t-test was used to analyze ordinal and continuous variables in an intent-to-treat analysis. Results: From December 2015 to January 2017, 20 women were enrolled, including 7 breast cancer survivors. Mean VMI for the study population was 25.1 (median 25) at baseline, and 21.4 (median 6) after 12 weeks of treatment (p>0.05). Similarly, there were no significant changes seen in mean VHI, which was 12.8 (median 13) at baseline and 14.1 (median 14) at 12 weeks (p>0.05). Statistically significant improvements were seen in both vaginal dryness and lubrication as reported by patients' scores. The mean vaginal dryness score for the population was 1.9 (median 2) at baseline and 1 (median 1) at 12 weeks (p<0.05). The effect was more pronounced in a subset of women (n=6) who did not use ultrasound jelly with their device (mean baseline score of 2.3 reduced to 1 at 12 weeks). Baseline vaginal lubrication scores (mean 0.6, median 1) for the population also improved after 12 weeks (mean 1.4, median 1, p<0.05), though the scores remained in the “mild” range. The six women who used the ultrasound device without jelly reported essentially no lubrication at the start of the study (mean 0.17, median 0), and had notably improved symptoms, reporting moderate lubrication after 12 weeks (mean and median score 1.5). Of the 15 women who completed the treatment according to protocol, 93% reported an improvement in at least one of their symptoms. Conclusions: Self-application of therapeutic ultrasound to the vaginal introitus decreased symptoms of vaginal atrophy in the majority of users. While no detectable changes in tissue physiology were noted with the VMI or VHI tools, the notable improvement in patient-reported outcomes warrants further study. A phase III clinical trial with a customized device is planned. Citation Format: MacLaughlan David S, Rockweiler H, Krone R, Middelton S, Blayney D. Developing a non-hormonal treatment for vaginal dryness for breast cancer survivors: A pilot study of a therapeutic ultrasound device [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P6-12-13.