The reaction of 2,3,6,2′,3′,4′,6′-hepta- O-acetyl-α-lactosyl bromide ( 4) and benzyl 3,4-di- O-benzyl-α- d-mannopyranoside ( 3) in the presence of mercury(II) cyanide in benzene-nitromethane produced benzyl 3,4-di- O-benzyl-2,6-bis- O-(2,3,6,2′,3′,4′,6′-hepta- O-acetyl-β-lactosyl)-α- d-mannopyranoside ( 5) and benzyl 3,4-di- O-benzyl-6- O-(2,3,6,2′,3′,4′,6′-hepta- O-acetyl-β-lactosyl)-α- d-mannopyranoside ( 6), as part of a complex mixture. Column chromatography, followed by acetylation of the fraction containing 5 and 6, gave a sample of 5 and benzyl 2- O-acetyl-3,4-di- O-benzyl-6- O-(2,3,6,2′,3′,4′,6′-hepta- O-acetyl-β-lactosyl)-α- d- mannopyranoside ( 7) in ∼ 35% and 17% yields (based on 4), respectively. Deprotection of 5 and 7 afforded the target compounds, namely 2,6-di- O-β-lactosyl-α,β- d-mannopyranoses and 6- O-β-lactosyl-α,β- d-mannopyranoses, respectively. If the coupling of 4 with 3 were performed in the presence of silver trifluoromethanesulfonate and 2,4,6-trimethylpyridine, only a mixture of 3,6,2′,3′,4′,6′-hexa- O-acetyl-α-lactose-1,2-{[3,6, 2′,3′,4′,6′-hexa- O-acetyl-α-lactose 1,2-(benzyl 3,4-di- O-benzyl-α- d-mannopyranosid-6-yl orthoacetyl)-2-yl] orthoacetate} and 3,6,2′,3′,4′,6′-hexa- O-acetyl-α-lactose 1,2-(benzyl 3,4-di- O-benzyl-α- d-mannopyranosid-6-yl orthoacetate) was obtained. The orthoacetates were characterized by n.m.r. spectroscopy. The two target materials are useful in the assessment of the binding properties of galactose-terminated ligands to the asialoglycoprotein receptor of normal rabbit and human hepatocytes.