Background: An anesthesiologist is expected to be able to manage intraoperative crises that can occur at any time. We aimed to determine the effectiveness of mindfulness-based intervention (MBI) technique in reducing stress levels of anesthesiology and intensive therapy residents at the Faculty of Medicine, University of Indonesia. Materials and Methods: This research was an experimental study with paired one group design. The MBI program lasted 4 weeks, consisted of one formal face-to-face training and 4 weeks of informal training (homework). Thirteen study subjects met the inclusion criteria and did not enter the exclusion criteria. One study subject was excluded because the subject did not complete the informal training. Data collection on the Perceived Stress Scale 10-Item (PSS-10) was conducted before and after training. Results: The average age of study subjects was 29.75 years; 75% are women. Four participants were in the 1 st year of education (33%), 3 participants were in the 2 nd year of education (25%), 2 participants were in the 3 rd year of education (16.67%), and 3 participants were in the 4 th year of education (25%). PSS-10 score in the study subjects significantly decreased after applying the MBI technique for 4 weeks (P = 0.001). Conclusion: MBI is effective in reducing stress levels of anesthesiology and intensive therapy residents at the-blinded.