The COVID-19 pandemic has taken its toll on everyone?s mental health. The medical frontliners, being one of the most exposed individuals to the virus, take on a high risk of facing a mental health crisis. Therefore, it is crucial to assess their mental health status. This study determines the impact of the COVID-19 pandemic on the mental health of the medical frontliners in Metro Manila. To gather data, adopted questionnaires: Depression, Anxiety and Stress Scale (DASS-21) and Impact of Event Scale with Modifications for COVID-19 (IES-COVID19) were utilized. These were disseminated through google forms via email. The data gathered were subjected to statistical analysis, with the help of statisticians, through Statistical Package for the Social Sciences (SPSS) Software. In this study, the statistical tools used were frequency, percentage, T-test, One-Way ANOVA, and regression analysis. From the results obtained, there were no significant differences in the demographic profiles, except for Anxiety before the pandemic and Stress during the pandemic in terms of age, and Anxiety and Stress before the pandemic in terms of the length of service. Based on the DASS-21 and IES-COVID19, the COVID-19 pandemic has a significant impact on the mental health of medical frontliners. There was an increase in terms of respondents with ?normal? results during the pandemic in comparison to pre-pandemic. According to regression analysis, the greatest impact of COVID-19 can be seen in depression, followed by anxiety, and stress. This knowledge can help in raising awareness regarding the mental health of medical frontliners and in assessing the appropriate interventions and protocols in healthcare institutions, especially during pandemic periods.