One of the most common methods for providing postoperative analgesia is via patient-controlled analgesia (PCA). Although the typical approach is to administer opioids via a programmable infusion pump, other drugs and other modes of administration are available. This article reviews the history and practice of many aspects of PCA and provides extensive guidelines for the practice of PCA-administered opioids. In addition, potential adverse effects and recommendations for their monitoring and treatment are reviewed.