The International Association for the Study of Pain (IASP) has recently introduced a new title "complex regional pain syndrome" to replace the confusing terminology of reflex sympathetic dystrophy and causalgia. This review article highlights the diagnostic criteria used and illustrates the necessity for such a change. The role of the sympathetic nervous system and the efficacy of sympathectomy in patients with sympathetically maintained pain are discussed. Controversies still exist regarding the use of various investigation tools, the results of which should be interpreted with caution. Finally, a multidisciplinary approach with different modalites to achieve the best success in breaking the cycle of pain and returning the patient to normal and productive function is the main aim of the treatment.