Neuropathic pain is caused by damage to the nervous system. Unlike physiologic pain (also known as nociceptive pain), neuropathic pain is not self-limited and is not as easily treated. The etiologic causes of neuropathic pain are many and varied in their scope. These include infectious agents, metabolic disease, neurodegenerative disease, and physical trauma, among others. Clinically, a high degree of variability exists between patients in their response to treatment. The pathophysiology of neuropathic pain syndromes is complex. However, current research is rapidly expanding our understanding of these syndromes. Numerous cellular mechanisms of pain transmission have been elucidated, and the clinical correlates of these mechanisms are beginning to be recognized. As our knowledge base continues to grow, we anticipate the development of improved treatments for the benefit of our patients with pain.