LBA10502 Background: Sexual harassment is a problem in the workplace, with a third of U.S. women reporting experiencing unwanted sexual advances in their careers. Moreover, gender disparities have persisted in medicine, despite over half of U.S. physicians under age 44 being female. The purpose of this study is to evaluate perceived gender biases, prevalence of sexual harassment, and how these affect physician growth and advancement in gynecologic oncology (Gyn-Onc). Methods: We conducted a survey study of U.S.-based physician members of the Society of Gynecologic Oncology: full, senior, and fellow members. Participants reported: demographics; experiences with sexual harassment in training/practice; perceptions of gender disparities in Gyn-Onc. Survey was anonymized and collected using RedCap data capture tool. Dichotomous outcomes were compared using Fisher’s exact test. Results: The survey was sent to 1,566 members; 402 responses were received (26% response rate: 255 females (F), 147 males (M)). Female responders were younger, non-white (28% F, 11% M), not married (16% F, 3% M), and had fewer years in practice than males (p≤0.001, each). Six of every 10 responders (64%) reported experiencing sexual harassment during training/practice; 7 of every 10 women (71%) experienced sexual harassment in training/practice. One in 10 responders openly reported this behavior (15% responders; 17%F, 10% M, p=0.210); most common reasons for lack of reporting were: incident did not seem important enough (40%), did not think anything would be done about it (37%), and fear of reprisal (34%). Female responders were more likely to report that they felt gender affected their career advancement (34% F, 10% M; p≤0.001) and that gender played a role in setting their salary (42% F, 6% M; p≤0.001). Of note, 91% male responders did not feel that there is a gender pay gap in Gyn-Onc, compared to 57% females (p≤0.001). Conclusions: This report is the first to show that experience of sexual harassment is common among Gyn-Onc physicians. Importantly, only few report these occurrences, often for fear of reprisal or concern that nothing will be done. Further, female Gyn-Oncologists report feeling that gender influences salaries and career advancement. Awareness and acknowledgement of sexual harassment and gender inequalities within Gyn-Onc can lead to interventions to address these disparities.