Abstract A series of derivatives of N-acetylneuramino-1,4-lactone diethyl dithioacetal has been investigated by n.m.r. spectroscopic techniques. The complete assignment of the 1H and 13C resonances was achieved by measurements of relaxation times, selective decoupling experiments, and two-dimensional shift-correlation spectroscopy. The conformational analysis of the acetylated derivative was based on J H,H values and nuclear Overhauser effects using the assignments of all the acetate groups. The influence of different substituents on the conformational behaviour is discussed.