20551 Background: The urogenital side effects of endocrine therapy for breast cancer are well recognized but neither their prevalence nor severity is well described in the non-trial setting. These symptoms can negatively impact quality of life (QoL) and may seriously impact the efficacy of therapy if they compromise adherence to the recommended endocrine treatment. Methods: In this questionnaire study, we utilized a 5-point Likert type scale to assess the prevalence and severity of vulvovaginal and urinary tract symptoms and we also assessed the impact of these symptoms on sexual functioning (Sexual Activity questionnaire) and QoL (FACT-ES questionnaire) in a group of post-menopausal women receiving endocrine therapy for adjuvant or metastatic breast cancer. We also asked if women considered non- adherence to treatment due to adverse effects. Results: 252 post-menopausal women were surveyed, with median age 60 (range 32–91). All women were currently receiving endocrine treatment for breast cancer; 84% in the adjuvant and 16% in the metastatic setting. Tamoxifen was used by 30% of women and Aromatase inhibitors by 67%. Of the women surveyed, 63% reported some degree of urogenital symptoms related to their treatment. 48% reported symptoms of vaginal dryness, 32% dyspareunia, 26% vaginal discharge, 27% vaginal itching/irritation, 5% vaginal bleeding and 12% reported urinary symptoms. 48% of patients who reported vaginal dryness had severe/very severe symptoms. Only 9 patients admitted that they had considered discontinuing treatment because of urogenital side effects. Conclusions: Urogenital side effects are common and were found in 63% of patients. The most common urogenital side effect reported was vaginal dryness, which was reported as severe or very severe in 48%. Despite this degree of severity, only 9 patients reported considering discontinuing therapy because of these side effects. No significant financial relationships to disclose.