No standardized criteria for the diagnosis of reflex sympathetic dystrophy (RSD) are in common use. An RSD score scoring system of diagnostic criteria is proposed. Diagnosis of reflex sympathetic dystrophy by RSD score correlated well with clinical diagnosis in a group of 25 patients who had treatment for chronic upper extremity pain. Standardization of diagnostic criteria with the RSD score should enhance comparison of the outcomes of studies concerning the treatment of RSD.