Lumbar sympathectomy was performed in twelve patients whose main or sole complaint was rectal tenesmus resulting from pelvic carcinoma, and in whom psychotropic drugs had failed to control their symptom. Following bilateral chemical lumbar sympathectomy, ten patients achieved complete relief and one patient achieved partial relief. No patient achieving relief had recurrence of their tenesmoid pain. Patients were followed up for between three days and seven months. No complications were noted except temporary hypotension in one patient. It is concluded that lumbar sympathectomy is a safe and effective treatment for rectal tenesmus and may be the treatment of choice if pharmacological methods have failed to control this symptom.