Rectal tenesmus is a persistent, painful and ineffectual sensation of straining at stool or opening of the bowels. Lumbar sympathectomy was performed in patient whose main complaint was rectal tenesmoid pain resulting from hemorrhoid operation, and in whom analgesic or psychotropic drugs had failed in controlling the symptom. After chemical lumbar sympathectomy, patient was free from the rectal tenesmoid pain. It is concluded that lumbar sympathectomy is a safe and effective treatment for rectal tenesmus.