The solution conformation of two lipooligosaccharides related to Nod factors or lipochitoligosaccharides have been analysed by 1D and 2D 1H and 13C NMR spectroscopy, molecular mechanics and dynamics calculations. The obtained data indicate that the glycosidic torsion angles have restricted fluctuations, but may adopt a variety of shapes. Remarkably, the relative orientation of the fatty acid chain towards the oligosaccharide backbone is solvent dependent. In water solution, the acyl residue and the oligosaccharide adopt a quasi-parallel orientation for a significant amount of time.