The objective of this study was to investigate the incidence, and the factors influencing the development, of complex regional pain syndrome-I in the upper extremity in hemiplegic patients within the first 28 weeks following a stroke. We followed up 82 stroke patients. All patients were evaluated at weeks 2, 6, 14 and 28 after suffering a stroke. Outcomes were assessed using passive range of motion of shoulder, presence of subluxation, Ashworth score, Motricity index arm score, Brunnstrom stages and depression score. The incidence of complex regional pain syndrome-I was 48.8% in the first 28 weeks. Significant correlation was found between complex regional pain syndrome-I and the presence of subluxation, Ashworth score, Motricity index arm score, Brunnstrom stage and depression score (r=0.259, P=0.019; r=0.271, P=0.014; r=-0.393, P<0.001; r=-0.385, P<0.001; r=0.293, P=0.008, respectively). In this study, there was a relationship between complex regional pain syndrome-I and subluxation, loss of range of motion, spasticity of shoulder muscles and muscle strength. In order to prevent the development of complex regional pain syndrome-I, exercises directed at increasing the range of motion for the glenohumeral joint, strengthening shoulder muscles and reduction of spasticity will establish the integrity of the shoulder joint. © 2007 Lippincott Williams & Wilkins, Inc.