Autopsies are an important tool for detecting diagnostic errors and improving clinicians' diagnostic performance. Review of autopsy case series over the past half century demonstrates a persistently high rate of clinically significant missed diagnoses, but despite this, autopsies are becoming increasingly uncommon in the United States. This Spanish study reviewed autopsies of patients who died in the intensive care unit of a teaching hospital over a 25-year period and found a missed diagnosis that would have affected therapy while the patient was alive in 7.5% of patients. Similar error rates have been found in other contemporary series, indicating that despite more advanced diagnostics, diagnostic error rates have likely not decreased significantly. Of note, in this series, 30.3% of patients who died underwent autopsy, a rate that is much higher than at most US institutions. A fatal missed diagnosis detected at autopsy is discussed in this AHRQ WebM&M commentary.