Background:The US government relies on nursing home-reported data to create quality of care measures and star ratings for Nursing Home Compare (NHC). These data are not systematically validated, and some evidence indicates NHC’s patient safety measures may not be reliable.Objective:The objective of this study was to assess the accuracy of NHC’s pressure ulcer measures, which are chief indicators of nursing home patient safety.Research Design:For Medicare fee-for-service beneficiaries who were nursing home residents between 2011 and 2017, we identified hospital admissions for pressure ulcers and linked these to the nursing home-reported data at the patient level. We then calculated the percentages of pressure ulcers that were appropriately reported by stage, long-stay versus short-stay status, and race. After developing an alternative claims-based measure of pressure ulcer events, we estimated the correlation between this indicator and NHC-reported ratings.Subjects:Medicare nursing home residents with hospitalizations for pressure ulcers.Measures:Pressure ulcer reporting rates; nursing home–level claims-based measure of pressure ulcer events.Results:Reporting rates were low for both short-stay (70.2% of 173,043 stage 2–4 pressure ulcer hospitalizations) and long-stay (59.7% of 137,315 stage 2–4 pressure ulcer hospitalizations) residents. Black residents experienced more severe pressure ulcers than White residents, however, this translated into having slightly higher reporting rates because higher staged pressure ulcers were more likely to be reported. Correlations between our claims-based measure and NHC ratings were poor.Conclusions:Pressure ulcers were substantially underreported in data used by NHC to measure patient safety. Alternative approaches are needed to improve surveillance of health care quality in nursing homes.