Two experiments tested the hypothesis that threatening people's self-esteem promotes transphobia. We manipulated state self-esteem by repeated subliminal priming of disparaging phrases (e.g., "I'm a failure"). We then measured transphobia by the Genderism and Transphobia Scale (Hill & Willoughby, 2015), and by presenting questions about a fictional trans man/woman. In Experiment 1, 60 cisgender heterosexual men were subliminally primed with either depressing or uplifting phrases in order to lower or enhance state self-esteem. A questionnaire administered after the manipulation confirmed that it indeed affected self-esteem. Results showed that participants were more transphobic in the low self-esteem condition. In Experiment 2, 120 cisgender heterosexual men and women went through a similar procedure, but this time we manipulated low vs. neutral self-esteem. Results replicated the results of Experiment 1, but the effect was more pronounced for men. In both experiments, and contrary to our prediction, participants were more negative towards a fictional trans man than towards a trans woman. Results highlight the need for enhancing self-esteem as a way to combat prejudice.