The results of our synthetic efforts and the investigation of the liquid-crystalline phase behaviour of a series of bis-mannosyl-amides are presented. In this investigation the structure of the polar carbohydrate groups was kept constant and the length of the terminal alkyl chain was varied between seven and twelve methylene groups. The results obtained from the DSC measurements, optical polarising microscopy and X-ray diffraction experiments will be reported and a structural model will be discussed.