This report presents a case of highly advanced gastric cancer that achieved a histologically complete response (CR) to preoperative chemoradiotherapy with S-1 plus low-dose Cisplatin. A 60-year-old male patient underwent FDG positron emission tomography (PET) during a routine health examination. The patient was found to have swollen paraaortic lymph nodes. Shortly thereafter, he was diagnosed with gastric carcinoma with a type 2 tumor in the antrum with paraaortic lymph node metastases based on FDG-PET, endoscopic examination and abdominal computed tomography. After the completion of chemoradiation therapy (CRT), the tumor and the paraaortic lymph node metastases disappeared. The patient underwent surgery 5 wk after the completion of CRT, including a subtotal gastrectomy with Rouxen-Y reconstruction, D3 lymph node dissection and a left adrenalectomy. No cancer cells were detected in the resected specimen either in the primary lesion or lymph nodes, thus confirming a pathologically CR to CRT (CR grade 3). The patient has been stable and well without any evidence of recurrence for 48 mo after surgery. Such a preoperative CRT regimen might therefore be very effective for treatment of some advanced gastric cancers.