Abstract: BACKGROUND ＆ AIM: To investigate the immunoregulatory and antitumor activities of Undaria pinnatifida extract. MATERIAL AND METHODS: Effects of Undaria pinnatifida extract on proliferation of spleen cells of mice were analyzed by 3H-TdR incorporation methods, effects of Undaria pinnatifida extract on stimulating tumor necrosis factor -α (TNF-α) secretion from mice monocytes were examined by a biological method, inhibition of tumor cells by Undaria pinnatifida extract with MTT technique. RESULTS: All concentrations of Undaria pinnatifida extract had effects of promoting the proliferation of spleen cells of mice. In vitro, undaria pinnatifida extract could activate mice monocytes to produce more TNF-α, and inhibited proliferation of four types of tumor cells. CONCLUSION: The present study indicateed that Undaria pinnatifida extract had the effects of promoting the proliferation of mice spleen cells, and induced mice monocytes to produce TNF-α.and significantly inhibited the growth of four kinds of tumer cells.

Key words: Undaria pinnatifada, tumor cell, tumor necrosis factor, proliferative assay of lymphocytes, immunoregulating activity