Purpose: To determine the spectrum of critical incidents in postanesthesia care unit (PACU) and the possible prediction and prevention of the worse scenario-associated critical incidents. Design: A retrospective observational study. Methods: The critical incidents in PACU comprising 92,136 patients were recorded. The incidents included the following disorders: delayed recovery, pain, bleeding, hypothermia, unplanned transfer to intensive care unit, shivering, agitation, nausea and vomiting, and respiratory or cardiovascular-related critical incidents. We then performed descriptive analyses and t test or c2 test on the collected data. Findings: A total of 1,760 critical incidents were recorded in 1,417 patients among 92,136 patients. Most critical incidents were associated with the patients after general anesthesia and general or gynecologic surgery. The most common critical incidents noted in the present study were pain, followed by cardiovascular-related and respiratory-related incidents. The average length of stay in PACU was 61.50 +/- 44.40 minutes for the patients with critical incidents and 28.50 +/- 19.40 minutes for the patients without critical incidents. Conclusions: Critical incidents lead to longer length of stay in the PACU. Regular inspection and immediate response for critical incidents in the PACU is essential for the maintenance of the quality of the immediate postoperative care. (c) 2020 American Society of PeriAnesthesia Nurses. Published by Elsevier, Inc. All rights reserved.