Purpose: This study examines various aspects related to medical professionalism in medical students during coronavirus disease 2019 (COVID-19) pandemic, focusing on their medical professionalism attributes, KPA (knowledge, practices, and attitudes) toward COVID-19 and attitudes toward provision of care in pandemic. We assessed whether these aspects related to medical professionalism were varied by their demographics and mental health level.Methods: Six questionnaires related to medical professionalism were distributed online to medical students in six grades at a single medical school. A one-way analysis of variance was used to examine differences in scores related to medical professionalism based on their demographics, for examples, gender, grade, residence, religion, as well as their mental health levels. Pearson correlation analysis was used to examine correlations between each variable.Results: Female students scored higher on medical professionalism attributes and attitudes toward duty-to-care than male students. Medical professionalism attribute scores were higher with higher relationship satisfaction and resilience levels but lower with higher anxiety levels. Furthermore, these scores were significantly associated with attitudes toward COVID-19 preparedness. However, COVID-19 knowledge and practice scores were negatively associated with attitudes toward COVID-19 preparedness and careers after graduation. Meanwhile, students who took the leave of absence related to 2020 doctors’ strike had significantly lower scores on attitudes toward COVID-19 preparedness and duty to care than those who did not.Conclusion: Our findings suggest that mental health of medical students is strongly related to their various aspects related to medical professionalism, especially their attitudes toward COVID-19 preparedness. Good mental health was positively linked to medical professionalism attributes and attitudes toward COVID-19 preparedness. However, knowledge and practice of COVID-19 were negatively associated with willingness to participate in the pandemic response. Additionally, the experience of the 2020 leave of absence impacted the attitudes of medical students toward COVID-19 preparedness (p=0.015) and their duty to care (p=0.012) negatively.