Reflex sympathetic dystrophy syndrome is characterized by variable complex of the following symptoms, such as pain, tenderness, vasomotor instability, and trophic changes in distal extremities resulting from injury to either central or peripheral nervous tissue. We measured blood flow using radioisotope angiography with agent containing technecium-99m in one patient with reflex sympathetic dystrophy syndrome. Blood flow were significantly lower in affected side than normal side. After epidural block with 0.5% lidocaine and left lumbar sympathetic block with 100% alcohol, burning pain was disappeared and blood flow was increased to near or above in relation to the normal side. Radioisotope angiography is a noninvasive study and not so expensive. And we thought that radioisotope angiography may be a useful aid not only for diagnosis, but also for evaluating therapeu-tic response.