Background: Although rectal tenesmus in patients with advanced cancer can have marked negative impact on quality of life, effective treatment has not yet been established. Case: A 71 -year-old man with an inoperable rectal cancer developed tenesmus 11 months after a colostomy. Tenesmus worsened over the following 3 months, and the patient suffered from involuntary straining every 5-15 minutes. After unsuccessful symptom control with radiotherapy to the primary lesion, we started oral amoxapine 25 mg that alleviated symptoms related to tenesmus. As the general condition deteriorated, however, oral intake became difficult. After the discontinuation of amoxapine, the tenesmus recurred even though intravenous administration of clomipramine was initiated. We started continuous infusion of intravenous lidocaine 200 mg/day which successfully relieved tenesmus. The dose of lidocaine was subsequently increased to 290 mg/day for worsening symptoms, which continued to control his distress caused by tenesmus until he died. Consideration/Conclusion: This is the first report that demonstrates the efficacy of oral amoxapine for rectal tenesmus with malignant tumor. After the discontinuation of amoxapine due to the inability of taking medications orally, symptoms remained under adequate control with infusional lidocaine until the patient died. Further studies are warranted to confirm our findings and to propose optimal use of medications in the management of rectal tenesmus.