Autopsy studies spanning five decades consistently show an error rate of almost 9%, implying that thousands of patients die every year due to diagnostic errors. Despite this sobering fact, a recent review found virtually no proven mechanisms for detecting or preventing errors in diagnosis. In this commentary, two experts in the patient safety field discuss the relationship between errors in the diagnostic process, missed or delayed diagnoses, and preventable adverse events, and the potential role of information technology in reducing diagnostic error risk. The authors propose a preliminary checklist for systematizing the diagnostic process for common symptoms. This commentary is based on a related article in the same issue that investigates diagnostic errors for a common medical presenting complaint.