Relationship between physical activity and mental health in students during the COVID-19 pandemic Objective of the research: To investigate the relationship between physical activity and mental health in students during the COVID-19 pandemic at the Faculty of Dental Medicine and Health Osijek. Study Design: A cross-sectional survey was conducted from the end of November 2020 to the end of January 2021. Participants and methods: 823 students participated in the research (153 male and 670 female). The data was collected through an online questionnaire consisting of three parts. The first part encompassed the general socio-demographic data of students and their self-assessment of mental stress and physical activity during the COVID-19 pandemic. The second part of the questionnaire included the DASS-21 scale (Depression Anxiety Stress Scale-21) and the third GSLTPAQ questionnaire (Godin-Shephard Leisure-Time Physical Activity Questionnaire). Results: Data from 823 students was processed, of which 650 (79%) nursing students, 94 (11.4%) physiotherapy students and 79 (9.6%) dental medicine students at the Faculty of Dental Medicine and Health Osijek, with the average age of 28 ± 9 years. Data showed that depression is in positive correlation with anxiety and stress. Concerning sex, women were more susceptible to increased mental stress, while physical activity in both sexes decreased. Undergraduate students have shown normal levels of depression, anxiety, and stress symptoms, while in graduate students, these levels were elevated. Undergraduate students were significantly more active than graduate students. Given the type of study, students of physiotherapy had the highest levels of depression, anxiety and stress symptoms but the highest physical activity levels. Conclusion: During the COVID-19 pandemic increased levels of depression, anxiety, and stress symptoms were observed, as well as a decreased physical activity among students at the Faculty of Dental Medicine and Health Osijek. An association between physical activity and mental health of students was not observed.