Liquid crystalline main chain polysiloxane esters have been formed by reacting bis[4-(ω-alkenyloxy)benzoic acid]esters containing 1,4-phenylene, 4,4′-biphenyldiyl, 2,7-fluorenediyl, and 2,7-fluorenonediyl units with, α,ω-di-H-oligo(dimethylsiloxane)s. The chemical structure has been confirmed by elemental analyses, IR,1H-NMR and13C-NMR spectroscopy. Molecular weights have been measured by GPC. The thermal behaviour has been studied by polarising microscopy and by DSC. In general the phase transitions are lower with a decreasing length of the alkylene spacers and with an increasing number of siloxane units within the spacer while they increase with magnification of the mesogenic groups. X-ray diffraction measurements for one polymer confirmed the type of the liquid crystalline phases (N, SC, SF). Deuteration has no influence on the thermal behaviour.