Abstract Thermotropic liquid‐crystalline polyesters with either 4,4″‐ p ‐terphenylylene or p ‐phenylene‐oxyterephthaloyloxy‐ p ‐phenylene as mesogenic units and dimethylsiloxane spacers in the main chain were synthesized. The thermal behaviour was studied by means of differential scanning calorimetry, polarizing microscopy, and X‐ray diffractometry. The polymers show mainly smectic mesomorphism. The transition temperatures were found to be much lower than in the corresponding polyesters containing polymethylene or poly(oxyethylene) spacers.