Introduction: Sexuality is a central aspect of being human, though its diversity is not completely accepted in society nor at medical schools. As a consequence, minority medical students face discrimination, poorer mental health, loneliness and worse academic performance. Objective: To investigate the sexual diversity of medical students and its possible influence on academic performance and mental health. Method: A descriptive cross-sectional study was conducted involving 187 undergraduate students of medicine. They answered a self-administrated multiplechoice questionnaire about their demographic characteristics, assigned sex at birth, sexual orientation, gender identity, whether sexual orientation and/or gender identity interferes with academic performance and whether they conceal their sexual orientation and/or gender identity. Participants also responded the Depression, Anxiety and Stress Scale (DASS-21) and questions about discrimination an loneliness. Results: Of the 187 undergraduate students of medicine that answered the questionnaire, 37,4% were LGBTQIA+ (lesbian, gay, bisexual), 62.5% were heterosexual and 100% were cisgender. Reported not openly assuming their sexuality 31.42% of the minority students. LGBTQIA+ accounted for 95, 72.90 and 81.82% of the students with extremely severe depression, anxiety and stress, respectively. Bisexual accounted for 63.63, 67.74 and 55.55% of LGBTQIA+ students with extremely severe depression, anxiety and stress, respectively. The majority of LGBTQIA+ students frequently felt alone (70%), isolated (72.85%) or excluded (68.58%). Most students (92.5%) reported their sexual orientation and/or gender identity did not affect their studies. Conclusion: LGBTQIA+ medical students present worse mental health (depression, anxiety and stress) and feel more excluded. Among them, bisexuals present greater vulnerability. Most medical students report their sexual orientation does not interfere with academic performance.