There are no adequate comparative studies on physical therapy (PT) versus occupational therapy (OT) in patients with complex regional pain syndrome I (CRPS I). Therefore, we conducted a prospective randomised clinical trial to assess their effectiveness. The outcomes regarding reducing pain and normalising active range of motion (AROM) are discussed. Included in the study were 135 patients who had been suffering from CRPS I of one upper extremity for less than one year. They were randomly assigned to one of three groups: PT, OT, or control (social work, CT). Measurements were taken at base-line (t0), after 6 weeks, and after 3, 6 and 12 months (t1 to t4). Pain was measured on four visual analogue scales (VAS) and the McGill Pain Questionnaire, Dutch Language Version (MPQ-DLV). The AROM was recorded relative to the contralateral side. Explorative statistical evaluations were performed (Wilcoxon; alpha=0.05). PT and to a lesser extent OT, resulted in more rapid improvement in the VAS scores than CT, especially for the VAS during or after effort (P<0.05 at t1 to t3). PT was superior to CT and OT according to the MPQ-DLV particularly at t4. Improvement on the MPQ-DLV over the year was significantly greater for PT than for OT and CT (P<0.05). PT -and to a lesser degree OT- led to better results than CT for the AROM of the wrist, fingers and thumb at t1 to t3 (most-times P<0.05 for PT), but the improvements over the year were not significantly different. Our results indicated that PT, and to a lesser extent OT, were helpful for reducing pain and improving active mobility in patients with CRPS I of less than one year duration, localised in one upper extremity.