Complex regional pain syndrome is a clinically challenging entity both in terms of accurate diagnosis and effective treatment. Complex regional pain syndrome is a post-traumatic painful neurologic syndrome involving the somatosensory, sympathetic and often the somatomotor systems. This complex condition consists of local neurogenic inflammation out of proportion to injury; severe pain in the skin, subcutaneous tissues and joints; and a central hyperexcitability that is often compounded with a sympathetic component. The syndrome is multifaceted manifesting both central and peripheral neurologic pathophysiology, frequently including a prominent psychosocial component. The wide array of possible patient presentations and antecedent pathologies also complicate successful treatment. To further add to the clinical challenges of complex regional pain syndrome, the epidemiology and natural history of complex regional pain syndrome are only partially known; evidence concerning complex regional pain syndrome treatment has grown slowly, due in large part to the vagaries of diagnosis; and research data--when they are available--are difficult to interpret. Thus, in spite of our evolving understanding of this neurologic disorder, in many cases complex regional pain syndrome remains difficult to diagnose and treat successfully.