Fucoidan is viscous fucose-rich polysaccharide derived from brown algae. Recently, the abalone enzyme-digested fucoidan extract derived from seaweed Mozuku of Clado-siphon novae-caledoniae kylin (fucoidan extract) draws much attention because of its clinical anti-cancer effect in Japan. The fucoidan extract suppressed the growth of mouse colon cancer cells in vivo. Here, we report the can-cer cell-specific apoptosis inducing effects of the fucoidan extract. The fucoidan extract suppressed the growth of various anchorage-dependent and independent cancer cells. The fucoidan extract contained low molecular weight components, which induced apoptosis of human leukemia HL60 cells but not of human lymphocytes, It has been known that sugar chain expression on the membrane surface of cancer cells changes dependent upon their malignancy. The analysis on sugar expression profiling using eight kinds of FTTC-labeled (Con A, DBA, LCA, PHA-E4, PNA, RCA120,UEA-I, WGA) revealed that the expression of Con A binding sugar chain was enhanced by the treatment of human lung adenocarcinoma A549, human uterine carcino-ma Hela, and human fibrosarcoma HT1080 cells with the fucoidan extract. Con A^induced apoptosis of cancer cells was stimulated in a dose-and time-dependent manner by the treatment with the fucoidan extract but not of human normal fibroblast TIG-1 cells.