The rapid progress in neurophysiology and neuropharmacology has made it possible to understand an entire series of pain-related processes. The discovery of endogenic opioid system, the noradrenergic and serotoninergic antinociceptive systems, peripheral opioid receptors and of the role of NMDA, muscarinic and nicotinic receptors in nociception allowed for an optimization of pain treatment through the use of new drugs and therapies. An appropriate pain treatment procedure prevents the development of persistent postoperative pain, which is described as a pathological chronic pain that endures following the operation despite normal healing process having taken place in affected tissues.