Objective: To determine the prevalence, type of complication, predisposing factors, and treatment for severe complications in a population of reflex sympathetic dystrophy (RSD) patients. Design: Retrospective analysis of the data from RSD patients collected over a 12-year period, to investigate the involvement of predisposing factors in an RSD population without severe complications compared with an RSD population with severe complications. Setting: Outpatient clinic of a department of surgery of a university hospital. Patients: A total of 1,006 patients with the diagnosis of RSD established according to prospectively defined criteria. Main Outcome Measures: The signs and symptoms of every RSD patient who visited the department were prospectively documented in the medical history; these data were retrospectively analyzed with special regard to RST) with severe complications-infection, ulcers, chronic edema, dystonia, and/or myoclonus-for prevalence, type of complication, and treatment. Results: Seventy-four RSD patients who were mostly young and female developed severe complications. More than one complication occurred in 91% of the affected extremities. Severe complications developed more frequently in the lower extremity (65%). In patients in whom the acute RSD started with a decreased skin temperature of the affected extremity, severe complications developed significantly more often than in acute RSD patients with a warm skin temperature of the extremity from the onset of the disease (p < .001). Conclusions: It is important to recognize "cold" RSD immediately at the onset of the disease because this group of RSD patients has a higher risk of developing a severe complication, mostly followed by a severe disability that is resistant to therapy. (C) 1998 by the American Congress of Rehabilitation Medicine and the American Academy of Physical Medicine and Rehabilitation.