Objective: To describe the prevalence of depression among medical students during the fourth wave of COVID-19 in Vietnam and its association with participation in working frontline.Methods: A cross-sectional study using an online questionnaire with a convenience sample of Hanoi Medical University students who were mobilized to support the frontline of the fight against COVID-19 was conducted. The study collected information regarding participation in the frontline and the mental health disorders using the Depression, Anxiety, and Stress Scale (DASS-21). Descriptive analysis, univariate linear and multivariate regressions were performed.Results: Over 16% of our sample reported mild to extremely severe depression. Almost two- third of participants of this group reported comorbidity for anxiety and stress. Findings indicated that depressive symptoms were negatively correlated with field tracing and testing work in the frontline. Conclusion: Our findings highlighted the relatively high prevalence of depression and the potentially high mental health problem comorbidity among frontline medical students inVietnam. Consequently, we recommend further research on frontline medical students, developing better workplace environment, appropriate interventions that address the link between depression and participation in the frontline, and trainings for junior healthcare workers.