Background: Safety in anesthesia can be improved through monitoring and analysis of anesthetic complications. We conducted the present Perioperative and Anesthetic Adverse Events in Thailand (PAAd Thai) incident reporting study to determine the current frequency distribution of incidents related to the anesthetic complications, factors contributing to the incidents, and corrective strategies. Objective: To describe the characteristics of the hospitals participating in this study and methods used. Methods: A multicenter prospective observational study was conducted in hospitals across Thailand in 2015. The participating hospitals were asked to anonymously report incidents of anesthesia-related adverse events and management. Three peer reviewers reviewed the completed record forms describing the incidents including possible mechanisms, contributing factors, appropriate management, and preventive strategies to achieve agreement by consensus. Results: Twenty-two hospitals across Thailand participated in this study. Fourteen (64%) were nonuniversity (service directed) hospitals, while 8 (36%) were university (academic teaching) hospitals. Most hospitals were involved in residency training and teaching medical students (77%), while just more than half (57%) were involved in training nurse anesthetists. The ratio of anesthesiologists to an operating room was 0.67:1 and the ratio of nurse anesthetists to an operating room was 2.03:1. Conclusion: A critical incident analysis of each reported adverse event is helpful for proposing a corrective or preventive strategy to ameliorate perioperative care and improve patient safety in the Thai health care system.