The purpose of this study was to develop a system to prevent laterality errors while performing peripheral nerve blockade. The report depicts 2 cases of peripheral nerve blocks being performed on the wrong (nonoperative) extremity. An analysis of the circumstances in each case reveals distractions, schedule changes, and communication breakdown, which contributed to the error. A protocol to prevent these errors from occurring in the future, based on the Joint Commission on Accreditation of Healthcare Organizations guidelines, to eliminate "wrong-site" surgical procedures is developed and discussed. The anesthesiologist plays an important role in preventing wrong-site peripheral nerve blockade and surgery. The protocol developed for "Pre-Anesthetic Site Verification" as a supplement to our preoperative site verification policy is invaluable in preventing wrong-site anesthesia and surgery.