Not until the late 1990s, after the publication of the National Academy of Medicine's treatise "To Err Is Human," did safety standards specifically for patients begin to be considered in operating room practices. This report and other studies documented operating room mistakes including, for example, operations on the wrong hand or limb, operations on the wrong patient, and the performance of wrong procedures. Cases have also been documented of sponges or instruments being left by mistake inside patients following surgery. Poor communication is the most common root cause of errors. This article explores these issues and explains procedures and protocols developed to reduce surgical errors.