Background: Burnout syndrome (BOS), a work-related constellation of symptoms and signs, causes individuals emotional stress and is associated with increasing job-related disillusionment. ICU-BOS among Thai intensivists and ICU nurses has never been clarified. Methods & materials: We performed a multicenter, prospective cross-sectional study in 17 hospitals in Thailand. BOS-related data were collected from full time ICU physicians and ICU nurses using electronic questionnaires. ICU-BOS was defined when participants exhibited at least 1 of 3 aspects (depersonalization, emotion exhaustion and personal accomplishment) regarding the Maslach Burnout Inventory. Primary outcome was prevalence of ICU-BOS among intensivists and ICU nurses, and secondary outcomes were risk factors for ICU-BOS. Results: After a total of 193 electronic surveys were sent, 171 responders (ICU physicians n=66, ICU nurses n=105) were included in this analysis (88.6%). Overall prevalence of ICU-BOS was 62.6%. Using multivariate analysis, the risk factors for ICU-BOS among intensivists were 1) income <20,000 THB, 2) feeling of quitting caring for patients in an ICU within the past year, 3) need >2 holidays/wk and 4) patient’s ICU-LOS >5 days (adjusted odd ratio (OR) of 31.5, 15.9, 7.4, 14.9; p =0.04, 0.007, 0.035, 0.004 respectively). Risk factors for ICU-BOS among ICU nurses were 1) age >40 years, 2) ICU experience >5 years, 3) patient’s ICU-LOS >5 days, 4) nurse to patient ratio lower than 1:1 5) feeling assignments in the ICU were too numerous and 6) feeling of quitting caring for patients in an ICU within the past year (adjusted OR of 15.7, 4.6, 10.0, 68.7, 4.3, 5.3; p =0.009, 0.04, 0.004, 0.004, 0.04, 0.007 respectively). Conclusion: In this study, we found a high prevalence of ICU-BOS among Thai intensivists and ICU nurses. Co-independent risk factors for BOS were patient’s ICU-LOS >5 days and feeling of quitting caring for patients in an ICU within the past year.