Introduction: The Coronavirus disease-2019 impacted the governments and public health systems worldwide, with the psychological impact including an increase in the level of stress, anxiety and depression. We determine the prevalence of depression, anxiety and stress using the Depression Anxiety Stress Scales (DASS-21), and to determine the psychological impact of COVID-19 pandemic amongst medical students in Sarawak, Malaysia using the revised Impact of Event Scale (IES-R). Methods: We analysed 355 medical student’s data obtained from an online survey. All the undergraduate medical students were the sample population. IBM SPSS version 22.0 was used for data analysis. A p-value of ≤.05 was considered statistically significant. Results: Analysis indicated that three-fourths of the students had no mental health issues. More than one-tenth of the students were moderately depressed (12.4%) and 4.3% severely depressed. A similar pattern of prevalence of anxiety was noted with 10% reported moderate anxiety, and 6.8% had severe anxiety. 15.8% of the students had mild stress, 4.2% moderately stressed, and 2% severely stressed. A hierarchical multiple linear regression analysis showed that hyperarousal appeared to be a predictor of depression (β=.466, p<.001), anxiety (β=.481, p<.001) and stress β=.508, p<.001). Along with hyperarousal, intrusion (β=.148, p<.05) predicts stress among the students. Conclusion: Our analysis revealed that hyperarousal symptoms related to the global pandemic of COVID-19 led to significant mental health issues among students. Therefore, urgent strategies to support the students’ psychosocial wellbeing and self-care and to strengthen their coping skills and resilience need to be implemented.