Abstract Background: Tamoxifen and Aromatase Inhibitors (AI) are highly effective forms of oral endocrine therapy (ET) used to prevent recurrences in women with hormone-receptor positive (HR+) breast cancer, often with a treatment duration of five or more years. However, the host of side effects women may experience, some related to vaginal health and sexual functioning, greatly impact quality of life (QoL). Those who experience side effects from oral ET are more likely to become non-adherent to their treatment protocol, adversely affecting survival outcomes. Despite this, general communication between cancer patients and their oncologists about sexual health is limited. Few studies have focused specifically on vaginal and sexual health when investigating ET side effects and patient-provider communication in women with HR+ breast cancer. This study aimed to determine the prevalence of vaginal and sexual-related side-effects in women with HR+ breast cancer on oral ET. Secondary objectives were to examine patient-provider communication around sexual health, female sexual dysfunction (FSD), and QoL in this patient population. Methods: We conducted a cross-sectional study between July 2017 and June 2018 in the outpatient oncology clinic at St. Michael’s Hospital (SMH), a tertiary-care center in Toronto, Canada. English-speaking women with HR+ breast cancer who had a treatment history with Tamoxifen or an AI (Anastrozole, Letrozole or Exemestane) for ≥ 6 consecutive months were eligible to participate. We developed a questionnaire to obtain self-reported information about vaginal and sexual-related side effects, sexual history, and patient-provider communication around sexual health. Two validated questionnaires were also used. Total scores for the Female Sexual Function Index (FSFI) could range from 1.2 to 36.0, with ≤ 26.55 indicating possible female sexual dysfunction (FSD). Domain scores within the 1-week recall version of the Menopause-Specific Quality of Life Questionnaire (MENQOL) range from one to eight, with higher scores indicating worse QoL. Additional demographic and clinical variables were collected from electronic medical records. Results: The mean age of the 151 respondents was 56.2 (±10.3), 51.0% of which were receiving Tamoxifen and 49.0% an AI. Ninety-six (63.6%) reported having a current sexual partner, and 71 (47.0%) reported being sexually active. Hot flashes/insomnia (41.7%), decreased libido (32.5%), and vaginal dryness (27.8%) were the three most commonly reported side effects that women experienced “all the time” in the past year. Only 44 (29.1%) women reported ever having been asked about their vaginal and/or sexual health by their oncologist, but 123 (81.5%) reported that they would be comfortable discussing this topic with them. Almost half of participants (68/151, 45.0%) indicated that their current vaginal or sexual-related side effects are not severe enough to want treatment. Thirty-four (22.5%) indicated wanting to know what their options are to best address side effects, 28 (18.5%) would be open to potential treatment for side effects, and 21 (13.9%) would be interested in seeing a physician specialist. Of the 87 women who fully completed the FSFI, 67 (77%) were classified as likely experiencing FSD. The mean score in the MENQOL’s sexual QoL domain was 3.89 ± 2.38 (n = 119), which indicated greater rates of vaginal dryness, avoidance of intimacy, and decreased sexual desire in this group. Conclusion: Our results support the notion that side effect management and patient-provider communication should be prioritized to optimize the vaginal and sexual health of women with HR+ breast cancer receiving oral ET. Women may be unaware of potential treatment options that can help manage side effects accompanying this therapy, and possibly accept these as a new standard of life. Citation Format: Amy Skitch, Alexandra Moskalewicz, Samantha Scime, Rosane Nisenbaum, Ronita Lee, Rashida Haq, Christine Dzerko, Christine Brezden-Masley. Vaginal and sexual health of hormone-receptor positive breast cancer survivors on oral endocrine therapy: A cross-sectional study [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr P2-12-07.