Sexual harassment (SH) is a widespread problem in academia, with a disproportionate impact on female medical students and those who experience marginalization via multiple systems of oppression (e.g. racism, heterosexism). Bystander intervention education is a potential approach which frames violence as a community issue where all members have a role to play in response and prevention. This study assessed the presence and influence of bystanders in SH situations for students at two medical schools. Data came from a larger U.S. campus climate study administered online in 2019 and 2020. The sample included 584 students who responded to validated survey questions about sexual harassment experiences, bystander behavior, disclosure, perceptions of the university response to SH, and demographics. More than one-third of respondents experienced some form of SH by a faculty/staff member. Bystanders were present for more than half of these incidents, yet they rarely intervened. When bystanders intervened, people were more likely to disclose an incident than not. The results indicate that there are many missed opportunities for intervention and given the profound impact that SH has on the well-being of medical students, continued work is needed to determine effective intervention and prevention methods. Practice points One-third of the medical students surveyed in our sample reported experiencing SH; women and LGBT medical students are more likely to experience SH than their counterparts. Bystanders are frequently present during SH incidents; however, the percentage of situations where bystanders actually intervened was extremely low. Bystander intervention was correlated with an increased likelihood to disclose. Thus, the implementation of bystander intervention education programs may help facilitate disclosure and reporting. Bystander intervention education programs are needed within academic medicine but must account for the role of power differentials. [ABSTRACT FROM AUTHOR]