Birefringence in thin layers of a star-shaped pentameric polyorganocyclosiloxane has been studied by the oblique polarized beam method. The coefficient of birefringence is measured in relation to temperature and thickness of the surface layer. On the basis of these data, the melting temperature of the compound concerned is determined and the orientational-order parameter is estimated as -0.27. The anisotropy of polarizabilities of pentameric polyorganocyclosiloxane molecules is theoretically estimated. A model of supramolecular structures that treats the formation of domains as stacks of pentameric polyorganocyclosiloxane molecules is advanced.