Complex regional pain syndrome (CRPS) sets in after an injury to a nerve or soft tissue that does not follow the normal healing path. The two types of CRPS are distinguished on the basis of absence of documented nerve injury in type 1 and documented nerve injury in type 2 called as causalgia. CRPS is assessed with both subjective complaints (medical history), and if present, objective findings (physical examination), in order to support the diagnosis. If diagnosed early, physicians can use mobilization of the affected extremity (physical therapy) and sympathetic nerve blocks to cure the disease. If untreated, CRPS can become extremely expensive due to permanent deformities and chronic pain. There is no single laboratory test to diagnose CRPS, however, there are a couple of tests i.e. thermogram and bone scan. There are three stages of CRPS. Stage 1 lasts for 3 months, stage 2 lasts from 3 to 6 months and stage 3 continues beyond 6 months. There are three reasons to consider sympathetic blockade to facilitate the management of CRPS which are described in this chapter. A sympathetic block of the upper extremity is called a stellate ganglia block (SGB). The SGB is performed by inserting a small needle alongside the trachea. Axillary sympathectomy, sympathectomy of the lower limb, postlaminectomy burning foot syndrome, postpelvic trauma CRPS, complications of sympathetic block, postsympathectomy pain, laparoscopic sympathectomy, etc. are other important topics which are covered in this chapter.