|Backgrounds) Treatment for lateral lymph node (LLN) metastasis largely differ between countries, and the impact of adding LLND to CRT still remains debatable.Patients) A total of 235 patients of locally advanced rectal cancer underwent neoadjuvant CRT and radical surgery. LLN of 8mm or more were defined as suspected LLN metastasis, and those without suspected LLN metastasis by pre-CRT imaging underwent total mesorectal excision (TME) without LLND (TME alone, n=207). Those with suspected LLN metastasis in pre-CRT imaging underwent TME+LLND. Of them, those with shrinkage of LLN p<8mm in post-CRT imaging was defined as LLN shrinkage group (n=7) and those with persistent LLN swelling even after CRT was LLN persistent group (n=20).Results) Of the TME alone group, 3 patients experienced recurrence in LLN area, suggesting that the incidence of LLN metastasis in this group was 1.4%. The incidence of actual LLN metastasis in LLN shrinkage group was 14.3%, whereas that in LLN persistent group was 80.0%. The 5-year local recurrence rate of TME alone, LLN shrinkage, and LLN persistent was 8.2%, 0% and 12.3%, respectively, whereas the 5-year distant metastasis rate was 19.7%, 14.3% and 34.6%.Conclusion) Although persistent LLN swelling even after CRT was indicative of distant metastasis recurrence, more than half of these patients resulted in cancer-free by additional LLND. LLND after CRT for selected patients should be a promising treatment option.