We reported a case of sigmoid colon cancer with left supraclavicular lymph node involvement that completely responded to FOLFOX4 therapy following laparoscopy-assisted colectomy (LAC). A 69-year-old female presented with left supraclavicular tumor and was diagnosed as sigmoid colon cancer. Abnormally high CEA (128 ng/mL) and CA19-9 (59.3 U/mL) levels were detected in serum. She was operated palliatively by LAC, and FOLFOX4 therapy was initiated. The serum CEA and CA19-9 values regained their normal level after 5 and 4 courses of FOLFOX4, respectively. After 5 courses, metastatic nodes disappeared on her CT. After 12 courses no abnormal accumulations were detected on FDG-PET. Antitumor efficacy was judged as CR. Grade 1 neutropenia and grade 2 peripheral neuropathy were noted, but no other serious adverse reactions occurred during FOLFOX4 therapy. CR has been maintained at present. She has been treated with FOLFOX4 therapy without oxaliplatin to prevent neuropathy. Establishment of maintenance therapy following CR to FOLFOX4 is awaited.