Purpose: The coronavirus disease 2019 (COVID-19) pandemic is a global health crisis that has impacted daily life due to the policies created to contain the outbreak. Recent studies showed that medical students, a high-stress population, experienced deteriorated mental well-being during the pandemic. The aim of the present study was to assess stress and the need for support among Thai medical students during the COVID-19 pandemic, as a multicenter study.Methods: The present study was a cross-sectional questionnaire-based study which collected data from second through sixth year medical students. Data was collected during the pandemic from multiple medical schools spanning all six regions of Thailand. Questionnaires included: demographic data; the Thai version of the Perceived Stress Scale-10 (T-PSS-10) assessing stress level and the sources of stress; and the received supports from medical schools, the satisfaction with the supports, and the further necessary needs.Results: There were 1,395 medical students who responded to the questionnaires. Mean T-PSS-10 score was 17.8. Most of the sources of stress were related to the changing of teaching and evaluation system. Students residing in larger medical schools were significantly more satisfied with received support and tended to gain greater support than those in medium and small sized schools. Stress-relieving activities arrangement was considered the most sought after additional support by students.Conclusion: Medical student stress levels were higher during the pandemic compared to pre-pandemic levels. Stress relieving activities, availability and access to mental health resources, and other strategies to reduce stress among medical students are urgently needed.