Moderate or severe pain are important sources of complications as well as morbidity and mortality in the postoperative period after surgical procedures. Patient-controlled analgesia (PCA) is an efective strategy for postoperative analgesia, since it may provide suitable analgesic dose just after system activation, with reduced periods of pain and an increase in patients' satisfaction. Although intravenous and epidural routes are the typical approaches used for PCA, regional patient-controlled analgesia has been shown to be an efective alternative providing a higher standard of analgesia with lower incidence of adverse efects. New devices and routes of PCA administration (transdermal, sublingual, inhalation, and oral routes) have shown to be promising alternatives in clinical studies. Nowadays, there is still no consensus regarding which is the best route or drug used since clinical eicacy/safety depends on the complex comprehension of the drugs pharmacokinetic proile through different routes of administration. Additionally, pharmacoeconomic studies are needed to evaluate the cost-efectiveness of these approaches.