A total of 57 patients, aged between 23 and 86 years, with complex regional pain syndrome (CRPS) type 1 nine weeks after an isolated closed fracture of the distal radius, was randomised to receive either serial intravenous regional blockade (IVRB) with 15 mg of guanethidine in 30 ml of 0.5% prilocaine or serial IVRB with 30 ml of normal saline at weekly intervals until the tenderness in their fingers had resolved or they had received a maximum of four IVRBs. The analgesic efficacy was assessed at 24 hours, 48 hours and one week after each procedure by the dolorimetry ratio and verbal pain scores, and at intervals up to six months after the fracture. There was no significant difference in the number of IVRBs administered or in finger tenderness, stiffness or grip strength between the two groups. The guanethidine group experienced more pain in the affected hand (p = 0.025) and at six months had more vasomotor instability (p < 0.0001) compared with the control group. IVRB using guanethidine offers no significant analgesic advantage over a normal saline placebo block in the treatment of early CRPS type 1 of the hand after fracture of the distal radius. It does not improve the outcome of this condition and may delay the resolution of vasomotor instability when compared with the placebo