Carbohydrate-protein interactions are known to be important in gamete interactions. Several evidence indicated that a fucose-containing sulfated polysaccharide fucoidan was potential inhibitor of fertilization in vitro and thus fucose seemed to be part of the recognition signal of gamete interaction in mammals. In recent investigation we found that α-L-fucosidase activity was present in boar spermatozoa and it was related to sperm binding to and penetration into zona pellucida (ZP) in vitro. The objective of this study was to determine the effects of monosaccharide L-fucose and polysaccharide fucoidan on sperm α-L-fucosidase activity and relation to sperm-oocyte interaction in pig. Results indicated that the activity of sperm α-L-fucosidase was largely inhibited (62%) when sperm suspension was treated with monosaccharide L-fucose. It also significantly inhibited the number of sperm binding to ZP (32%) and penetration into zona-intact oocytes (72%), but did not inhibit penetration into zona-free oocytes when fertilization medium contained Lfucose. The chlorotetracycline (CTC) assessment showed that L-fucose did not affect induction of sperm capacitation and acrosome reaction. In contrast, the activity of sperm α-L-fucosidase was not inhibited when sperm suspension was treated with polysaccharide fucoidan but sperm-ZP binding was greatly inhibited (85%) and completely blocked sperm penetration into zona-intact or zona-free oocytes. The CTC assessment showed that fucoidan increased the F pattern and decreased the AR pattern sperm. These results suggested that the different inhibitory mechanisms were present between monosaccharide L-fucose and polysaccharide fucoidan on sperm-oocyte interaction, the inhibition effect of α-L-fucose on sperm binding and penetrating into ZP caused sperm α-L-fucosidase inhibited by α-Lfucose.