Rubber elasticity is a unique feature of polymer networks or elastomers formed from long polymer chains connected to one another by crosslinkages. An implanting of rod-like mesogenic monomer units into the network chains can induce the liquid crystalline state of the elastomers. The interplay between network chain conformation and liquid crystalline phase creates material with remarkable properties. Detailed investigations proved a direct coupling between chain conformation and anisotropic state of order of the liquid crystalline phase. Introducing an anisotropic chain conformation a priori by a suitable synthesis concept, networks can be obtained that are macroscopic uniformly ordered (liquid single crystal elastomers, LSCE). Depending on the liquid crystalline phase structure, LSCE exhibit exceptional properties, e.g. nematic LSCE change their macroscopic dimensions when the state of order is modified by external stimuli. This effect can be applied to novel thermo- and opto-mechanical actuators.