A 60-year-old woman was diagnosed as having duodenal cancer by upper gastrointestinal endoscopy and biopsy. Pylorus-preserving pancreatoduodenectomy was performed. Pathological findings suggested T4(CBD)N1M0 primary duodenal carcinoma. Adjuvant chemotherapy with S-1(80 mg/m² of S-1 administered for 2 weeks followed by a 1-week drug-free period)was administered after surgery. One year after the surgery, computed tomography(CT)scans showed swelling of the paraaortic lymph nodes. Recurrence of the duodenal carcinoma was diagnosed, and gemcitabine chemotherapy was initiated. Eight months later, CT scans revealed lung metastasis. The patient was then treated with oxaliplatin in combination with infusional 5-fluorouracil/Leucovorin(FOLFOX regimen). After completing 6 courses of the chemotherapy regimen, CT scans showed a partial response(PR). Currently, at 1 year, PR has been maintained. Therefore, we suggest that the FOLFOX regimen can be highly effective for the treatment of patients with duodenal carcinoma.