The structure and function studies of complex carbohydrates by nuclear magnetic resonance techniques has been hampered by the lack of both new methods for oligosaccharide assembly and appropriately stable isotope labeled precursors. Despite these limitations the body of experimentally derived 3D sugar structures is growing rapidly. With the advent of the Danishefsky solid phase synthetic method for construction of oligosaccharides (and other useful methods) we have embarked on a program to provide stable isotope labeled monomers for such methods and to investigate their use in solution NMR spectroscopic studies. The SIR has developed synthesis of the monomers, of D-[1,2,3,4,5,6- 13c 61glucal and D- [ 1,2,3,4,5,6- 13C 61galactal. from commercially available D-[U_13C]glucose. Live and co-workers have reported the first use of 13 C-labeled monomers in the Danishefsky solid phase method for the construction of a Lewisy determinant and have begun solution structure NMR studies on these labeled tetrasaccharides.