Physical exercise is a planned and structured physical activity with a final objective that constitutes a non-communicable diseases preventive tool and a physical and mental health protective factor. Likewise, the motivations for doing exercise are essential and it can be influenced by gender. The purpose of this study is to consider the differences about the motivations of doing exercise based on gender and to analyse the relationship between physical exercise and perceived physical and mental health. To achieve this objective, a sample of 600 young university students (50% men and 50% women), completed the online questionnaire about Lifestyle and Health (Giménez-García Ballester-Arnal, 2017). The analysis showed significant differences in the regular physical exercise between men (61.7%) and women (45.3%) (Chi 2=16.01; p≤.001). Moreover, gender differences in motivations for doing exercise were observed in all motivations, except for the motivation about “to be thinner” (Chi 2=1.00; p= .317), being men who exceed women for all of them. In relation to the motivations for not doing exercise, there are differences for the motivations “lack of time” (Chi 2=7.72; p= .005), “being short of time” (Chi 2=5.40; p= .020) and “Lack of force of will” (Chi 2=8.26; p= .004), being more relevant for women. Moreover, people who practiceexercisereport better perceived physical (t=7.87; p≤.001)and mental (t=2.31; p= .021) health. Therefore, gender differences about frequency and motivations for doing exercise exist and are related to gender stereotypes. Additionally, people who do greater levels of physical exercise, have a better physical and mental health perception.