Piriformis syndrome, a term applied to an abnormal condition of the piriformis muscle, is characterized by symptoms and signs due to sciatic nerve entrapment at the greater sciatic notch. Recently we reviewed a case of unusual low back pain, radiating to the left lower extremity with tenderness particular in the left buttock. The patient was successfully treated by sectioning the piriformis tendon. We described the clinical features of a case of piriformis syndrome and reviewed the foreign literature.