espanolObjetivo: Este estudio fue realizado con el proposito de determinar la eficacia analgesica de los bloqueos del ganglio estrellado, en el alivio del dolor mediado por el sistema nervioso simpatico, en pacientes con sindrome doloroso regional complejo. Pacientes y metodos: Se realizo un ensayo clinico controlado con asignacion aleatoria y enmascaramiento simple. Treinta y nueve pacientes fueron tratados con una serie de bloqueos de ganglio estrellado, terapia fisica y tratamiento farmacologico, mientras que treinta y dos pacientes fueron tratados con fisioterapia y el mismo esquema farmacologico. Para determinar la asociacion entre las variables se utilizo el riesgo relativo con sus respectivos intervalos de confianza. Resultados: En la evaluacion clinica realizada un mes postratamiento se encontro alivio del dolor en 84,6% de los pacientes del grupo de intervencion y en 78,1% de los controles (RR= 1,08; I.C. 95%=0,8-1,4; p=0.48), sin encontrarse diferencias estadisticamente significativas. No se encontro asociacion entre la eficacia analgesica y tabaquismo, dominancia, genero, tipo de SDRC, causa desencadenante y nivel educativo. EnglishObjective: The purpose of this study was to determine the analgesic efficacy of stellate ganglion blockade in pain mediated by the sympathetic nervous system in patients with Complex Regional Pain Syndrome (CRPS). Patients and methods: A randomized, simple-blinded controlled clinical trial was conducted. Thirty nine patients were randomly assigned to an intervention group which was treated with a series of stellate ganglion blockades, physical therapy and pharmacological treatment, and thirty two to a control group which was treated with physical therapy and the same pharmacological treatment. Risk ratio was used to evaluate outcome and determine association with predictor variables. Results: At the end of the first month post treatment, it was found that 84.6% of patients in the intervention group had alleviation of their pain while 78.1% of the control group had alleviation of their pain; there was not a statistically significant difference (RR=1.08; C.I. 95%=0.8-1.4; p=0.48). We found no association between analgesic efficacy, smoking, dominance, gender, and type of CRPS, unleashing cause or educational level.