We evaluated the relationship between the size of regional lymph nodes and the presence of metastasis in them in rectal cancer. Of 1,064 lymph nodes in 46 specimens, 133 (13%) were found to have metastases. A half of the positive nodes and most of the negative ones were less than 5 mm in diameter. Therefore, we must find lymph nodes smaller than 5 mm in diameter for assessment of lymph node metastasis. Although positive nodes were larger than negative ones, there was no significant difference. However, when comparing the size of lymph nodes in relation to their location, the epi- and pararectal lymph nodes larger than 10 mm in diameter were highly suggestive of metastases, but the size of the lymph node was not a reliable indicator of lymph node metastases in other situations.