The syntheses and X-ray analyses of two fucopyranosides, the monosaccharide benzyl 3,4-di-O-acetyl-2-hydroxy-beta-D-fucopyranoside, C(17)H(22)O(7), and the disaccharide 1-benzyl O-(2,3-di-O-acetyl-4,6-O-benzylidene-beta-D-glucopyranosyl)-(1-->2)-3,4-O-isopropylidene-beta-D-fucopyranoside, C(33)H(40)O(12), are described. The different substituents induce small conformational changes on the fucopyranoside ring. However, the conformation of the benzyl group varies from (+)gauche for the monosaccharide to synperiplanar for the disaccharide.