This document discusses medical errors and misdiagnosis. It notes that one in five medical errors are potentially serious or fatal, and that the most common reasons for medical malpractice claims are surgery errors and diagnostic errors. Diagnostic errors account for many preventable deaths annually in the US. Some of the leading causes of misdiagnosis discussed include lack of healthcare professionals, poor teamwork and follow up, human cognitive factors, and too much focus on one exam finding. The document also provides strategies to reduce errors such as thorough history taking, physical exams, using diagnostic aids, and always following up on concerning symptoms.