This study inquired into the mechanism of cancer lymphatic metastasis. The immunohistochemistry method and DNA hybridization in situ were employed in examining the peritumoral rectum tissues and metastatic lymph nodes from 8 rectum carcinoma patients and the rectum tissues and lymph nodes from 5 normal subjects. The results showed that the proteins of ICAM-1 and nuclear factor kappa B (NF kappa Bp65) were expressed on the lymphatic endothelial cells of the rectum adenocarcinoma patients, and there was a NF kappa B binding consensus sequences on ICAM-1 promoter in lymphatic endothelial cells of rectum adenocarcinoma patients. When DIG-AKP labeled 38 bp oligonucleotide probe was used, there was no the expression of ICAM-1 and NF kappa Bp65 on the lymphatic endothelial cells of the normal human lymph node and rectum tissues. It is suggested that the activation of ICAM-1 promoter may critically depend on NF kappa Bp65 homodimers or heterodimers binding to a variant kappa B site on the lymphatic endothelial cells of the rectum adencarcinoma of human. These observations may indicate the potential roles of NF kappa B in cancer metastasis, thus giving clues to facilitate the development of a novel anti-metastasis strategy, that is obstruction the NF kappa B-activation pathways.