Background: Gender bias induces gender inequality in health. In this study, we evaluated gender bias during a local objective structured clinical examination (OSCE). Methods: We assessed gender bias by using two clinical cases—generalized anxiety disorder (GAD) and ascending aorta dissection (AAD)—during an OSCE performed among fifth-year medical students. For each situation, half of the students encountered male and half encountered female standardized patients (SPs). Except for gender, variables were identical in each clinical case. Patients, students, and examiners were blinded to the purpose of the study. Medical history, clinical examination, diagnosis, and management were compared between male and female SPs. The interaction between student and SP gender was analyzed. Results: A total of 110 medical students were observed (55% women). For GAD, students arrived at the correct diagnosis more often for female SPs than for male SPs (diagnosis completed, partially completed, and not completed in 47%, 16%, and 36%, respectively, of female SPs vs. 22%, 20%, and 58%, respectively, of male SPs, p = 0.02). The nature of their symptoms was more often asked of male SPs (completed, partially completed, and not completed in 51%, 4%, and 0% of male SPs, respectively, vs. 38%, 17%, and 0% of female SPs, respectively, p = 0.002), and associated physical symptoms were more often explored in female SPs (completed and not completed in 84% and 16% of female SPs, respectively, vs. 65% and 35% of male SPs, respectively, p = 0.03). For AAD, an emergency was better identified in female SPs (95% identified in female SPs vs. 76% in male SPs, p = 0.005) and examination of femoral pulses was more often performed in female SPs (88% completed in female SPs vs. 54% in male SPs, p < 0.0001). The interaction between SP and student gender was not significant. Conclusion: The gender bias observed supports the need to address unconscious biases and to raise student awareness of gender stereotypes likely to lead to underrecognition or subtreatment of disease in patients of both genders.