Objective: To examine the level of burnout syndrome, and to investigate the relationship between burnout, personality traits, coping strategies, and other related personal factors among mental health professionals working in a tertiary hospital.Materials and Methods: Online questionnaires were sent to 160 mental health professionals at Siriraj Hospital. The questionnaire comprised questions collecting demographic data, the Copenhagen Burnout Inventory (Thai version), the Big Five Inventory, and the Coping Scale. The data were analyzed through descriptive statistics, analysis of variance, Pearson correlation, and stepwise multiple regression.Results: A total of 121 (75.6%) responses were collected. Of the 121 participants, 41.3% reported high total burnout levels. However, no difference in total burnout was found between the different mental health professions. The group aged between 20-29 years demonstrated higher burnout than the others. Individuals with bachelor’s and master’s degrees showed greater burnout than those with lower than undergraduate degrees. Moreover, individuals who worked for less than five years had higher burnout than those in other groups. Furthermore, neuroticism and avoidance significantly predicted the burnout syndrome.Conclusion: In contrast to previous studies in Thailand, the results highlighted the risk factors for burnout syndrome in terms of personal, work-related, and client-related burnout. These results can strengthen awareness surrounding mental health conditions, for the effective provision of psychoeducation and psychological interventions.