Some new theories concerning pain physiology have recently been suggested. Experimental facts show that despite its complexity, neuroplasticity is an established fact. The concept of preemptive analgesia is about to receive clinical applications. Nevertheless, the role of many opioid ligands which are involved in the pain physiology can explain the efficacy of some analgesia techniques. The authors review the physiological process of pain from its periphery to its centre and the ensuing practical applications. They point out the difficulty to apprehend peripheral analgesia, and the necessity of further researches concerning especially NMDA spinal receptors and other specific receptors.