The AHRQ Patient Safety Indicators (PSIs), which are used to screen administrative data for patient safety events, have been revised in response to the new ICD-10 coding system. This study sought to validate the accuracy of ICD-10-based PSIs for detecting postoperative adverse events, compared to the National Surgical Quality Improvement Program reference standard. Although the PSIs had relatively high negative predictive value (meaning that the absence of a PSI meant that the patient likely had not experienced an adverse event), the overall accuracy was not sufficient to warrant using PSIs as the sole strategy to detect adverse events.