Patient perspectives have been shown to identify otherwise undetected adverse events. This Institute for Healthcare Improvement–National Patient Safety Foundation commissioned survey, an update to their original 1997 survey, interviewed a probability-based sample of 2536 American adults. The results demonstrate the widespread nature of patient safety problems. Overall, 20% of respondents reported personally experiencing a medical error, most often in the outpatient setting. However, only 10% of respondents said they experienced harm when receiving medical care, which underscores the contrast between error and harm. The most common type of error was a missed or delayed diagnosis, followed by a communication error. About a third of errors were not reported. These results highlight the need to focus on diagnostic safety in the outpatient setting in order to improve patient safety in United States health care.