Bias in teaching evaluations has been documented across academia. Women and people from non-white minority groups receive lower ratings from students when compared to white males. Student evaluations of teaching (SET) play an important role in assessing instructors’ teaching quality, and thus impact hiring, promotion, and tenure decisions. Similarly, student ratings of teaching assistants (TA) can impact future career opportunities. We investigated gender bias in student evaluations of TAs. Students in a large, asynchronous, online course were deceptively assigned to either a putative male or putative female TA. In reality, one female TA performed all TA duties, grading assignments and communicating with students under the guise of each student’s assigned TA. Overall, evaluations were positive, however, evaluations of the putative male and female TAs demonstrated inconsistency across student gender. Female students demonstrated the greatest variation; 100% of females assigned to the “male” TA rated the TA positively, whereas 88% of female students assigned to the “female” TA gave positive ratings. This study corroborates literature demonstrating bias against women in SET. The lack of strong statistical trends in our study could indicate a shift in student perspective or demonstrate that gender bias is muted in the asynchronous online learning environment.