An inaccurate definition of what constitutes sex can negatively impact the sexual health and wellbeing of patients. This study aimed to determine which behaviors medical students consider to be sex. Survey questions about various sexual behaviors were administered to medical students. All participants agreed that penile-vaginal penetration is sex. More than 25% of participants did not consider genital-genital contact without penetration, oral-genital contact, foreign object in rectum, and forced vaginal/rectal penetration as sex. Nonheterosexuals were more likely to consider genital-genital contact without penetration sex. We determined there was less than complete consensus among future physicians on what activities are considered sex.