Purpose: Moral distress occurs when one identifies an ethically appropriate course of action but cannot carry it out. In this conceptualization, medical students may be particularly vulnerable to moral distress, but the literature on moral distress in medical trainees remains sparse. Method: Using content analysis of 802 reflective essays written by third-year medical students, the authors analyzed for the presence of moral distress and other ethical themes. The authors then used chi-squared analysis to determine which ethical themes were statistically associated with moral distress. Results: Two hundred and seventy-four (34%) of the essays included student descriptions of moral distress. The most frequent theme in the moral distress essays was “role of the medical student” in the training hierarchy, and this reached a statistically significant association with moral distress (χ2=15.19, p < 0.001). Statistically significant associations (p < 0.05) were also found with moral distress and themes related to an “ethical disagreement with supervisor,” “insensitive care,” “disputes,” “abuse,” “poverty,” “medical errors,” and “transplant ethics.” Essays discussing the “doctor–patient relationship” or observations of a “job well done” were statistically less likely to involve moral distress. Conclusions: Moral distress is a common occurrence in medical students, particularly related to medical students’ role in the training hierarchy or other difficult interpersonal and clinical interactions. In our sample, moral distress was described less often in the presence of positive role models.